Rubber compositions containing whey protein

ABSTRACT

The present disclosure is directed to rubber compositions comprising a conjugated diene rubber, a reinforcing silica filler, and a whey protein component. The whey protein component is in an amount sufficient to provide about 0.1 to about 10 phr whey protein. The present disclosure is also directed to methods of preparing such rubber compositions and to tire components containing the rubber compositions disclosed herein.

FIELD OF THE DISCLOSURE

The present disclosure relates to rubber compositions comprising atleast one rubber, a reinforcing silica filler and a whey proteincomponent, and to related methods. The present disclosure also relatesto tire components containing the rubber compositions disclosed herein.

BACKGROUND

Rubber compositions for vehicles tires frequently use reinforcingfillers, such as silica, to impart desirable properties such as abrasionresistance and rolling resistance. However, silica fillers canagglomerate (during mixing) in rubber compositions, which causes theviscosity of the composition to increase. Increased viscosity makes therubber composition more difficult to process.

SUMMARY OF THE INVENTION

Disclosed herein are rubber compositions comprising at least one rubber,a reinforcing silica filler and a whey protein component, and relatedmethods. Also disclosed are tire components containing the rubbercompositions disclosed herein.

In a first embodiment, a rubber composition comprising at least onerubber, a reinforcing silica filler, and a whey protein component isdisclosed. The rubber composition comprises about 5 to about 200 phr ofthe reinforcing silica filler, and the whey protein component is presentin an amount sufficient to provide about 0.1 to about 10 phr of wheyprotein.

In a second embodiment, a rubber composition that has been subjected tocuring is disclosed; the composition comprises at least one rubber, areinforcing silica filler, whey protein, and a cure package. The rubbercomposition comprises about 5 to about 200 phr of the reinforcing silicafiller, and the whey protein is present in an amount of about 0.1 toabout 10 phr.

In a third embodiment, a method for reducing the viscosity of asilica-filler-containing rubber composition is disclosed. The methodcomprises the use of a rubber composition comprising at least onerubber, about 5 to 200 phr of a reinforcing silica filler, and a wheyprotein component in an amount sufficient to provide about 0.1 to about10 phr of whey protein.

DETAILED DESCRIPTION

Disclosed herein are rubber compositions comprising at least one rubber,a reinforcing silica filler and a whey protein component, and relatedmethods. Also disclosed herein are tire components containing the rubbercompositions disclosed herein.

In a first embodiment, a rubber composition comprising at least onerubber, a reinforcing silica filler, and a whey protein component isdisclosed. The rubber composition comprises about 5 to about 200 phr ofthe reinforcing silica filler, and the whey protein component is presentin an amount sufficient to provide about 0.1 to about 10 phr of wheyprotein.

In a second embodiment, a rubber composition that has been subjected tocuring is disclosed; the composition comprises at least one rubber, areinforcing silica filler, whey protein, and a cure package, isdisclosed. The rubber composition comprises about 5 to about 200 phr ofthe reinforcing silica filler, and the whey protein is present in anamount of about 0.1 to about 10 phr.

In a third embodiment, a method for reducing the viscosity of asilica-filler-containing rubber composition is disclosed. The methodcomprises the use of a rubber composition comprising at least onerubber, about 5 to 200 phr of a reinforcing silica filler, and a wheyprotein component in an amount sufficient to provide about 0.1 to about10 phr of whey protein.

Definitions

The terminology as set forth herein is for description of theembodiments only and should not be construed as limiting the inventionas a whole.

As used herein, the term “phr” means the parts by weight of rubber. Ifthe rubber composition comprises more than one rubber, “phr” means theparts by weight per hundred parts of the sum of all rubbers.

As used herein, the term “polybutadiene” is used to indicate a polymerthat is manufactured from cis-1,3-butadiene monomers. The termpolybutadiene is also used interchangeably with the phrase“polybutadiene rubber” and the abbreviation “BR.”

As used herein, the term “polyisoprene” means synthetic polyisoprene. Inother words, the term is used to indicate a polymer that is manufacturedfrom isoprene monomers, and should not be construed as includingnaturally occurring natural rubber (e.g., Hevea natural rubber,guayule-sourced natural rubber or dandelion-sourced natural rubber). Theterm polyisoprene is also used interchangeably with the phrase“polyisoprene rubber” and the abbreviation “IR.”

As used herein, the term “styrene-butadiene rubber” or “SBR” means acopolymer manufactured from styrene and cis-1,3-butadiene monomers.

As used herein, the term “natural rubber” or “NR” means naturallyoccurring rubber such as can be harvested from sources such as Hevearubber trees, and non-Hevea source (e.g., guayule shrubs, and dandelions(e.g., TKS)). In other words, the term “natural rubber” should not beconstrued as including polyisoprene.

As used herein, the term “whey protein component” means a componentwhich contains whey protein, but which also may include other materialssuch as water, minerals, fats, carbohydrates, etc.

As used herein, the term “majority” means at least 51% by weight.

As used herein, the term “minority” means less than 50% by weight.

For the purpose of this disclosure, any reference to a percent amount ofa component in the rubber composition means a percent by weight, unlessotherwise specified. Similarly, any reference to ratios of componentamounts in the rubber composition means the ratios by weight, unlessotherwise specified. Unless stated to the contrary, discussions hereinrelating to the components and amounts of the rubber compositions of thepresent disclosure should be understood to apply equally to the otherembodiments, e.g., the related methods and the tires (and tire treads)containing the rubber compositions disclosed herein.

Whey Protein Component and Whey Protein

As discussed above, according to the first and second embodimentsdisclosed herein, the rubber composition comprises a whey proteincomponent and according to the second embodiments disclosed herein, therubber composition comprises whey protein. As discussed in more detailbelow, the whey protein component is the source of whey protein in theresulting rubber composition.

Whey protein and casein protein are two types of protein found in milk(i.e., milk from cows, goats, sheep, humans, or other mammals). Wheyprotein refers generally to a group of milk proteins that remain solublewhen liquid milk is acidified to a pH of 4.6 or lower. Casein proteinsare the milk proteins that coagulate at acidic pH to become cheese,yogurt, or another solidified or semi-solidified milk product. After thecoagulated casein protein solids are removed from acidified milk, theremaining liquid is referred to as whey; the whey typically containswhey protein along with varying amounts of carbohydrates (e.g.,lactose), fats, and minerals.

Whey protein is a collection of globular proteins, which includesproteins such as alpha-lactalbumin, beta-lactoglobulin, immunoglobulin,and bovine serum albumin; while whey protein comprises a collection ofproteins, for ease of reference it is referred to herein as “wheyprotein” in the singular. The combination of alpha-lactalbumin andbeta-lactoglobulin comprise the majority of the proteins in whey proteinfrom cow's milk, comprising about 25% and 65%, respectively, by weightof the protein. Although whey protein may comprise very minor amounts ofindividual amino acids or short-chain protein oligomers, the majority(i.e., more than 50%, including more than 75%, more than 90%, or evenmore than 95%) of the protein chains in whey protein have a molecularweight greater than about 10 k Daltons (measured by a method such as gelelectrophoresis). In certain embodiments of the first-third embodimentsdisclosed herein, the protein chains of the whey protein used in therubber composition (or contained in the whey protein component) have adegree of hydrolysis that is less than about 50%. The degree ofhydrolysis (“DH”) is the percentage of peptide bonds cleaved when aprotein is hydrolyzed to break the protein chain into shorter chains orindividual amino acids. DH can be measured by any of several knownmethods, including pH stat measurement, trinitrobenzenesulfonic acid(TNBS) reaction, ortho-phthaldialdehyde (OPA) reaction, and formoltitration. In certain embodiments of the first-third embodimentsdisclosed herein, the whey protein used in the rubber composition (orcontained in the whey protein component) has a DH that is less thanabout 30%, including less than 30%, less than about 25%, less than 25%,less than about 20%, less than 20%, less than about 15%, less than 15%,less than about 10%, less than 10%, less than about 5%, less than 5%,less than about 3%, and less than 3% DH. In certain embodimentsaccording to the first-third embodiments disclosed herein, the wheyprotein in the whey protein component meets at least one of thepreceding attributes relating to DH.

All proteins are comprised of building blocks of amino acids. Theprotein chains of whey protein contain a relatively high percentage ofbranched-chain amino acids (BCAAs), particularly leucine. Due to theamino acid profile of whey protein, it contains significant amounts ofsulfur, but no phosphate (phosphorus). Thus, in certain embodiments, thewhey protein component used in the rubber compositions or the wheyprotein contained in the rubber compositions according to thefirst-third embodiments can be described as phosphate (or phosphorus)free. Casein protein, in contrast, has a different amino acid profileand comprises primarily alpha-caseins, beta-casein, and kappa-casein.Due to the amino acid profile of casein protein, it contains significantamounts of phosphate (phosphorus), but little sulfur.

Whey with a pH of about 5.1 or greater is called “sweet whey,” and is abyproduct of hard cheese production. Sweet whey protein is commerciallyvaluable for making ricotta cheese and as an animal feed or fertilizer.However, the whey that results from making soft cheese, cottage cheese,and yogurt typically has a pH less than 5.1. This so-called “acid whey”and the acid whey protein in it have traditionally had little commercialvalue.

When whey is first separated from milk, the whey is mostly water (e.g.,greater than about 90% water by weight), but it also contains wheyproteins, fats, carbohydrates (e.g., lactose), minerals (e.g., calcium),and other milk-based materials (e.g., cholesterol). Thus, for thepurpose of this disclosure, whey may be considered a whey proteincomponent. However, the high aqueous content of most whey and itsrelatively low protein content (generally less than 1%) makes its use asa whey protein component in the rubber compositions according to thefirst-third embodiments disclosed herein possible, although lesspreferred. To make a more practical whey protein component for use inthe rubber compositions (or source of whey protein) according to thefirst-third embodiments disclosed herein, the whey may be processed toremove some or all of the water, increase the concentration of the wheyproteins, remove non-protein materials, or combinations of theforegoing. Such processed forms of whey are commercially available andmay be sold under names including acid whey powder, reduced lactosewhey, reduced minerals whey, sweet whey powder, whey powder concentrate,and whey protein isolate. Accordingly, in certain embodiments of thefirst-third embodiments disclosed herein the whey protein componentcomprises (or the whey protein is sourced from) at least one of acidwhey powder, reduced lactose whey, reduced minerals whey, sweet wheypowder, whey protein concentrate, and whey protein isolate. In certainof the foregoing embodiments, the whey protein component (or wheyprotein) is sourced from cow's milk (due to the general prevalence ofcow's milk), and in other embodiments it is sourced from a non-humananimal.

In certain embodiments according to the first-third embodimentsdisclosed herein, the whey protein component (or source of the wheyprotein) comprises a powder (i.e., whey powder). Whey powder may beformed by drying liquid whey (i.e., acid whey or sweet whey) to a solid,scoopable powder (i.e., acid whey powder or sweet whey powder). Wheypowder may still have some residual water in the composition, but isessentially a dry powder when used as a whey protein component. Incertain embodiments according to the first-third embodiments disclosedherein, the whey protein component (or source of the whey protein)comprises acid whey powder, sweet whey powder, or a combination thereof.In certain such embodiments, the acid whey powder comprises about 10 toabout 15% by weight protein. In another embodiment of the first-thirdembodiments disclosed herein, the whey protein component (or source ofthe whey protein) comprises reduced lactose whey. Reduced lactose wheymay be formed by treating liquid whey to remove some or all of the waterand lactose to form reduced lactose whey. In certain embodiments of thefirst-third embodiments disclosed herein, the reduced lactose wheycomprises about 15 to about 30% by weight (including 15 to 30% byweight) protein. In another embodiment of the first-third embodimentsdisclosed herein, the whey protein component (or source of the wheyprotein) comprises reduced minerals whey. Reduced minerals whey may beformed by treating liquid whey to remove some or all of the water andminerals (e.g., calcium) to form reduced minerals whey. In certainembodiments of the first-third embodiments disclosed herein, the reducedminerals whey comprises about 10 to about 15% by weight protein(including 10 to 15% by weight). In another embodiment of thefirst-third embodiments disclosed herein, the whey protein component (orsource of the whey protein) comprises whey protein concentrate (WPC).WPC may be formed by treating liquid whey to remove a significantportion of the water. WPC may still have other milk components (e.g.,fats, lactose, minerals, etc.) present in significant amounts. Incertain embodiments of the first-third embodiments disclosed herein, theWPC comprises about 30 to about 85% by weight (including 30 to 85% byweight) protein. In another embodiment of the first-third embodimentsdisclosed herein, the whey protein component (or source of the wheyprotein) comprises whey protein isolate (WPI). WPI may be formed bytreating liquid whey to remove much of the water, fat, lactose, andother non-protein components. In certain embodiments of the first-thirdembodiments disclosed herein, the WPI comprises at least about 90%protein by weight (including at least 90% protein by weight).

As discussed above, according to the first-third embodiments disclosedherein, the rubber composition comprises a whey protein component (or asource of whey protein) in an amount sufficient to provide about 0.1 toabout 10 phr whey protein in the rubber composition. In certain suchembodiments, the whey protein component is present in an amountsufficient to provide 0.1 to 10 phr (e.g., 0.1 phr, 0.2 phr, 0.25 phr,0.3 phr, 0.4 phr, 0.5 phr, 1 phr, 2 phr, 3 phr, 4 phr, 5 phr, 6 phr, 7phr, 8 phr, 9 phr, 10 phr) of whey protein in the rubber composition,including about 0.2 to about 9 phr, including 0.2 to 9 phr, includingabout 0.25 to about 8 phr, including 0.25 phr to 8 phr, including about0.3 to about 7 phr, including 0.3 to 7 phr, including about 0.4 to about6 phr, including 0.4 to 6 phr, including about 0.5 to about 5 phr, andincluding 0.5 to 5 phr whey protein in the rubber composition. Theamount of whey protein component needed to provide the foregoing amountsof whey protein will vary depending upon the concentration of wheyprotein in the respective whey protein component

As discussed above, in certain embodiments according to the first-thirdembodiments disclosed herein, sources for the whey protein componentused in the rubber composition (and, accordingly, the whey proteincontained in the rubber composition) include manufacturers of acidwhey-based dairy products, such as producers of Greek yogurt, cottagecheese, and other soft cheeses. In certain embodiments of thefirst-third embodiments disclosed herein, sources for the whey proteincomponent used in the rubber composition (and, accordingly, the wheyprotein contained in the rubber composition) include commercial wheyprotein products, including but not limited to acid whey powder, sweetwhey powder, reduced lactose whey, reduced minerals whey, WPC, WPI, andcombinations thereof.

Polymers (Rubbers)

As discussed above, according to the first-third embodiments disclosedherein, the rubber composition comprises at least one rubber. Theserubber compositions can be understood as comprising 100 parts of rubber(100 phr), which includes at least one rubber. The at least one rubbercan be selected from natural rubber, synthetic rubber, or combinationsthereof. Suitable rubbers for use in the rubber composition are wellknown to those skilled in the art and include but are not limited to thefollowing: synthetic polyisoprene rubber, natural rubber,styrene-butadiene rubber (SBR), styrene-isoprene rubber,butadiene-isoprene-rubber, styrene-isoprene-butadiene rubber,polybutadiene, butyl rubber (both halogenated and non-halogenated),neoprene (polychloroprene), ethylene-propylene rubber,ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber(NBR), silicone rubber, fluorinated rubber, polyacrylate rubber(copolymer of acrylate monomer and vinyl ether), ethylene acrylicrubber, ethylene vinyl acetate copolymer (EVA), epichlorohydrin rubbers,chlorinated polyethylene rubbers, chlorosulfonated polyethylene rubbers,nitrile rubber, halogenated nitrile rubber, hydrogenated nitrile rubber,tetrafluoroethylene-propylene rubber, and combinations thereof. Examplesof fluorinated rubber include perfluoroelastomer rubber,fluoroelastomer, fluorosilicone, and tetrafluoroethylene-propylenerubber.

In certain embodiments of the first-third embodiments disclosed herein,at least a majority (by weight) of the at least one rubber comprises atleast one of: natural rubber, polyisoprene rubber, polybutadiene rubber,and styrene-butadiene rubber; in such embodiments, one or more than onetype of any of the foregoing rubbers can be utilized. In certainembodiments, at least 60% by weight (at least 60 parts or phr), at least70% by weight (at least 70 parts or phr), at least 80% by weight (atleast 80 parts or phr), at least 90% by weight (at least 90 parts orphr), at least 95% by weight (at least 95 parts or phr), or even 100% byweight (100 parts or phr) of the rubber comprises at least one of:natural rubber, synthetic polyisoprene rubber, polybutadiene rubber, andstyrene-butadiene rubber.

In certain embodiments of the first-third embodiments disclosed herein,a minority (by weight) of the at least one rubber comprises at least oneof: styrene-isoprene rubber, butadiene-isoprene-rubber,styrene-isoprene-butadiene rubber, butyl rubber (both halogenated andnon-halogenated), neoprene (polychloroprene), ethylene-propylene rubber,ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber(NBR), silicone rubber, fluorinated rubber, polyacrylate rubber(copolymer of acrylate monomer and vinyl ether), ethylene acrylicrubber, ethylene vinyl acetate copolymer (EVA), epichlorohydrin rubbers,chlorinated polyethylene rubbers, chlorosulfonated polyethylene rubbers,nitrile rubber, halogenated nitrile rubber, hydrogenated nitrile rubber,and tetrafluoroethylene-propylene rubber. In certain embodiments, up to40% by weight (up to 40 parts or phr), up to 30% by weight (up to 30parts or phr), up to 20% by weight (up to 20 parts or phr), up to 10% byweight (up to 10 parts or phr), up to 5% by weight (up to 5 parts orphr) of the rubber comprises at least one of: styrene-isoprene rubber,butadiene-isoprene-rubber, styrene-isoprene-butadiene rubber, butylrubber (both halogenated and non-halogenated), neoprene(polychloroprene), ethylene-propylene rubber, ethylene-propylene-dienerubber (EPDM), acrylonitrile-butadiene rubber (NBR), silicone rubber,fluorinated rubber, polyacrylate rubber (copolymer of acrylate monomerand vinyl ether), ethylene acrylic rubber, ethylene vinyl acetatecopolymer (EVA), epichlorohydrin rubbers, chlorinated polyethylenerubbers, chlorosulfonated polyethylene rubbers, nitrile rubber,halogenated nitrile rubber, hydrogenated nitrile rubber, andtetrafluoroethylene-propylene rubber. In other embodiments, 0% by weight(0 parts or phr) of the rubber comprises styrene-isoprene rubber,butadiene-isoprene-rubber, styrene-isoprene-butadiene rubber, butylrubber (both halogenated and non-halogenated), neoprene(polychloroprene), ethylene-propylene rubber, ethylene-propylene-dienerubber (EPDM), acrylonitrile-butadiene rubber (NBR), silicone rubber,fluorinated rubber, polyacrylate rubber (copolymer of acrylate monomerand vinyl ether), ethylene acrylic rubber, ethylene vinyl acetatecopolymer (EVA), epichlorohydrin rubbers, chlorinated polyethylenerubbers, chlorosulfonated polyethylene rubbers, nitrile rubber,halogenated nitrile rubber, hydrogenated nitrile rubber, andtetrafluoroethylene-propylene rubber; in such embodiments, 100 phr ofthe rubber comprises at least one of: natural rubber, syntheticpolyisoprene rubber, polybutadiene rubber, and styrene-butadiene rubber.In yet other embodiments, up to 100% by weight (100 phr), including upto 90% by weight (90 phr), up to 80% by weight (80 phr), up to 70% byweight (70 phr) and up to 60% by weight (60 phr) of the rubber comprisesat least one of: styrene-isoprene rubber, butadiene-isoprene-rubber,styrene-isoprene-butadiene rubber, butyl rubber (both halogenated andnon-halogenated), neoprene (polychloroprene), ethylene-propylene rubber,ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber(NBR), silicone rubber, fluorinated rubber, polyacrylate rubber(copolymer of acrylate monomer and vinyl ether), ethylene acrylicrubber, ethylene vinyl acetate copolymer (EVA), epichlorohydrin rubbers,chlorinated polyethylene rubbers, chlorosulfonated polyethylene rubbers,nitrile rubber, halogenated nitrile rubber, hydrogenated nitrile rubber,and tetrafluoroethylene-propylene rubber.

In certain embodiments of the first-third embodiments disclosed herein,the at least one rubber comprises a polymer, a copolymer, or acombination thereof (i.e., more than one polymer, more than onecopolymer, one polymer and one copolymer, more than one polymer and onecopolymer, more than one copolymer and one polymer, or more than onecopolymer and more than one polymer) when more than one rubber isutilized. In certain embodiments of the first-third embodimentsdisclosed herein, the at least one rubber includes at least oneconjugated diene monomer-containing polymer or copolymer. Examples ofsuitable conjugated diene monomers according to certain embodiments ofthe first-third embodiments disclosed herein include, but are notlimited to, 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene,2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene,2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, 2,4-hexadiene, 1,3-cyclopentadiene,1,3-cyclohexadiene, 1,3-cycloheptadiene, and 1,3-cyclooctadiene, andderivatives thereof. It should be understood that mixtures of two ormore conjugated dienes may be utilized in certain embodiments.Non-limiting examples of suitable polymers that are conjugated dienemonomer-containing polymers or copolymers include, but are not limitedto, styrene-butadiene rubber, polybutadiene, polyisoprene,styrene-isoprene rubber, styrene-butadiene-isoprene rubber, and naturalrubber. In certain embodiments of the first-third embodiments disclosedherein, the at least one rubber is at least one of: styrene-butadienerubber, polybutadiene, synthetic polyisoprene rubber, and naturalrubber.

As discussed above, in certain embodiments according to the first-thirdembodiments, the at least one rubber comprises polybutadiene. In certainembodiments according to the first-third embodiments, the polybutadienecomprises a high cis polybutadiene. In certain embodiments according tothe first-third embodiments, the high cis polybutadiene has a cis1,4-bond content of 85% of greater, 90% or greater, 92% or greater, or95% or greater. In certain embodiments of the first-third embodiments,the polybutadiene has a cis 1,4-bond content of 85-99%, 90-99%, 90-98%,90-97%, 92-99%, 92-98%, 92-97%, 95-99%, 95-98%, or 95-97%.

Generally, various polymerization methods are known for producingpolybutadiene having a cis 1,4-bond content of 85% or greater, 90% orgreater, 92% or greater, or 95% or greater and it should be understoodthat the particular method by which the polybutadiene is produced is notlimited as long as the resulting polybutadiene has the specified cis1,4-bond content. The percentages are based upon the number of diene merunits adopting the cis-1,4 linkage versus the total number of diene merunits. Polymerization of high-cis 1,4-polybutadiene is described in U.S.Pat. Nos. 3,297,667, 3,541,063, 3,794,604, 4,461,883, 4,444,903,4,525,594, 4,699,960, 5,017,539, 5,428,119, 5,064,910, and 5,844,050,7,094,849, all of which are hereby incorporated by reference. Exemplarypolymerization methods include, but are not limited to, those employingZiegler-Natta catalysts based on transition metals (e.g., lanthanidessuch as neodymium), nickel catalysts and titanium-based catalysts aswell as solution, emulsion and bulk polymerization processes. Generally,the cis 1,4-, vinyl 1,2-, and trans 1,4-bond linkage contents in a givenpolymer such as polybutadiene can be determined by standard andwell-established analytical methods such as infrared spectroscopy.

As discussed above, in certain embodiments according to the first-thirdembodiments, the at least one rubber comprises polyisoprene. In certainembodiments according to the first-third embodiments, the polyisoprenecomprises high cis polyisoprene. In certain embodiments according to thefirst-third embodiments, the high cis polyisoprene has a cis 1,4-bondcontent of 90% of greater. In certain embodiments of the first-thirdembodiments, the polyisoprene has a cis 1,4-bond content of 90% orgreater, 92% or greater, or 95% or greater. In certain embodiments ofthe first-third embodiments, the polyisoprene has a cis 1,4-bond contentof 90-99%, 90-98%, 90-97%, 92-99%, 92-98%, 92-97%, 95-99%, 95-98%, or95-97%.

Generally, various polymerization methods are known for producingpolyisoprene, including polyisoprene having a cis 1,4-bond content of90% or greater, and it should be understood that the particular methodby which the polyisoprene is produced is not limited as long as theresulting polymer has the desired cis 1,4-bond content. As previouslydiscussed with respect to polybutadiene, the percentages are based uponthe number of diene mer units adopting the cis-1,4 linkage versus thetotal number of diene mer units. Polymerization of high-cis polyisopreneis described in U.S. Pat. Nos. 8,664,343; 8,188,201; 7,008,899;6,897,270; and 6,699,813, all of which are hereby incorporated byreference. Exemplary polymerization methods include, but are not limitedto, those employing Ziegler-Natta catalyst systems and those employinganionic polymerization with organometallic catalysts such as alkyllithium in hydrocarbon solvents. As previously discussed with respect topolybutadiene, the cis-1,4-, cis-1,2-, and trans-1,4-linkage contents ina given polymer such as polyisoprene can be determined by standard andwell-established analytical methods such as infrared spectroscopy.

As discussed above, in certain embodiments according to the first-thirdembodiments, the at least one rubber comprises the copolymerstyrene-butadiene rubber (SBR). SBR is a copolymer of styrene andbutadiene monomers. In certain embodiments according to the first-thirdembodiments disclosed herein, the SBR used in the rubber compositioncomprises about 10 to about 50% styrene monomer and about 50 to about90% butadiene monomer by weight. In certain embodiments according to thefirst-third embodiments disclosed herein, the SBR used in the rubbercomposition comprises 10 to 50% styrene monomer and 50 to 90% butadienemonomer by weight. Generally, SBR is produced by solution or emulsionpolymerization methods; however, it should be understood that theparticular method by which the SBR is produced is not limited. Thestyrene and butadiene monomer content in a given SBR copolymer can bedetermined by standard and well-established analytical methods such asinfrared spectroscopy.

Numerous commercial sources of the foregoing rubbers are well-known. Asnon-limiting examples, Firestone Polymers offers various grades of itsDiene™ polybutadiene which have varying cis 1,4-bond contents (e.g., 40%and 96%) as well as various grades of its Duradene™ solution polymerizedstyrene-butadiene copolymer. Other commercial sources of the rubbers arewell known, including sources for emulsion polymerized styrene-butadienecopolymer, functionalized versions of styrene-butadiene copolymer,neoprene, polybutadiene, synthetic polyisoprene rubber, and naturalrubber.

In certain embodiments according to the first-third embodimentsdisclosed herein, the at least one rubber of the rubber compositioncomprises a functionalized polymer. In certain such embodiments, therubber composition comprises about 5 to about 100 parts or phr of atleast one functionalized polymer, including 5 to 100 parts or phr, about10 to about 90 parts or phr, 10 to 90 parts or phr, about 10 to about 70parts or phr, 10 to 70 parts or phr, about 10 to about 50 parts or phr,and 10 to 50 parts or phr. In certain embodiments according to thefirst-third embodiments disclosed herein, the functionalized polymercomprises a polymer with a silica-reactive functional group, anitrogen-containing functional group, an oxygen-containing functionalgroup, a sulfur-containing functional group, or a combination of theforegoing. Non-limiting examples of silica-reactive functional groupsthat are known to be utilized in functionalizing conjugated dienepolymers and are suitable for use in the rubber compositions of certainembodiments of the first-third embodiments disclosed herein includenitrogen-containing functional groups, silicon-containing functionalgroups, oxygen or sulfur-containing functional groups, andmetal-containing functional groups. As used herein, the termfunctionalized polymer should be understood to include polymers(including conjugated diene monomer-containing polymer or copolymerrubbers) with a functional group at one or both terminus (e.g., from useof a functionalized initiator, a functionalized terminator, or both), afunctional group in the main chain of the polymer, and combinationsthereof. For example, a silica-reactive functionalized polymer may havethe functional group at one or both terminus, in the main chain thereof,or both in the main chain and at one or both terminus.

Non-limiting examples of nitrogen-containing functional groups that areknown to be utilized in functionalizing rubbers include, but are notlimited to, any of a substituted or unsubstituted amino group, an amideresidue, an isocyanate group, an imidazolyl group, an indolyl group, anitrile group, a pyridyl group, and a ketimine group. The foregoingsubstituted or unsubstituted amino group should be understood to includea primary alkylamine, a secondary alkylamine, or a cyclic amine, and anamino group derived from a substituted or unsubstituted imine. Incertain embodiments according to the first-third embodiments disclosedherein, the rubber composition comprises a functionalized conjugateddiene monomer-containing polymer or copolymer rubber having at least onefunctional group selected from the foregoing list.

Non-limiting examples of silicon-containing functional groups that areknown to be utilized in functionalizing rubbers include, but are notlimited to, an organic silyl or siloxy group, and more precisely, thefunctional group may be selected from an alkoxysilyl group, analkylhalosilyl group, a siloxy group, an alkylaminosilyl group, and analkoxyhalosilyl group. Suitable silicon-containing functional groups foruse in functionalizing rubbers also include those disclosed in U.S. Pat.No. 6,369,167, the entire disclosure of which is hereby incorporated byreference. In certain embodiments according to the first-thirdembodiments disclosed herein, the rubber composition comprises afunctionalized rubber having at least one functional group selected fromthe foregoing list.

Non-limiting examples of oxygen or sulfur-containing functional groupsthat are known to be utilized in functionalizing rubbers include, butare not limited to, a hydroxyl group, a carboxyl group, an epoxy group,a glycidoxy group, a diglycidylamino group, a cyclic dithiane-derivedfunctional group, an ester group, an aldehyde group, an alkoxy group, aketone group, a thiocarboxyl group, a thioepoxy group, a thioglycidoxygroup, a thiodiglycidylamino group, a thioester group, a thioaldehydegroup, a thioalkoxy group and a thioketone group. In certainembodiments, the foregoing alkoxy group may be an alcohol-derived alkoxygroup derived from a benzophenone. In certain embodiments according tothe first-third embodiments disclosed herein, the rubber compositioncomprises a functionalized conjugated diene monomer-containing polymeror copolymer rubber having at least one functional group selected fromthe foregoing list.

Generally, rubbers, including conjugated diene monomer-containingpolymer or copolymer rubbers, may be prepared and recovered according tovarious suitable methods such as batch, semi-continuous, or continuousoperations, as are well known to those having skill in the art. Thepolymerization can also be carried out in a number of differentpolymerization reactor systems, including but not limited to bulkpolymerization, vapor phase polymerization, solution polymerization,suspension polymerization, coordination polymerization, and emulsionpolymerization. The polymerization may be carried out using a freeradical mechanism, an anionic mechanism, a cationic mechanism, or acoordination mechanism. All of the above polymerization methods are wellknown to persons skilled in the art. However, for exemplary purposes, ashort description of polymerization via an anionic mechanism is given.

When rubbers, such as conjugated diene monomer-containing polymer orcopolymer rubbers, are produced through anionic polymerization, anorganic alkaline metal compound, preferably a lithium-containingcompound, is typically used as a polymerization initiator. Examples oflithium-containing compounds used as polymerization initiators include,but are not limited to, hydrocarbyl lithium compounds, lithium amidecompounds, and similar lithium compounds. The amount of the lithiumcompound used as the polymerization initiator is preferably within arange of 0.2 to 20 millimoles per 100 g of the monomer.

Non-limiting examples of hydrocarbyl lithium compounds include ethyllithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyllithium, tert-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyllithium, 2-butyl-phenyl lithium, 4-phenyl-butyl lithium, cyclohexyllithium, cyclopentyl lithium, a reaction product of diisopropenylbenzeneand butyl lithium, and mixtures thereof. Among these, alkyl lithiumcompounds such as ethyl lithium, n-propyl lithium, isopropyl lithium,n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl lithiumand so on are preferable, and n-butyl lithium is particularlypreferable.

Methods for producing rubbers, such as conjugateddiene-monomer-containing polymer or copolymer rubbers, through anionicpolymerization using an organic alkaline metal compound as thepolymerization initiator are not particularly limited. For example, aconjugated diene monomer-containing polymer or copolymer rubber can beproduced by polymerizing a conjugated diene monomer alone or a mixtureof a conjugated diene monomer and aromatic vinyl compound in ahydrocarbon solvent inactive to the polymerization reaction.Non-limiting examples of the hydrocarbon solvent inactive to thepolymerization reaction include propane, n-butane, isobutane, n-pentane,isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene,trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene,benzene, toluene, xylene, ethylbenzene and mixtures thereof.

The anionic polymerization may be carried out in the presence of arandomizer. The randomizer can control the microstructure of theconjugated diene compound, and has an action that the 1,2-bond contentin butadiene unit of the polymer using, for example, butadiene as amonomer is controlled, and butadiene unit and styrene unit in thecopolymer using butadiene and styrene as a monomer are randomized, orthe like. Non-limiting examples of the randomizer includedimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycoldibutyl ether, diethylene glycol dimethyl ether, bis tetrahydrofurylpropane, triethylamine, pyridine, N-methylmorpholine,N,N,N′,N′-tetramethyl ethylenediamine, 1,2-dipiperidinoethane,potassium-t-amylate, potassium-t-butoxide, sodium-t-amylate and so on.The amount of the randomizer used is preferably within a range of 0.01to 100 molar equivalents per 1 mol of the organic alkaline metalcompound as a polymerization initiator.

The anionic polymerization may be carried out through any of solutionpolymerization, vapor phase polymerization and bulk polymerization. Inthe solution polymerization, the concentration of the monomer in thesolution is preferably within a range of 5 to 50% by mass, morepreferably 10 to 30% by mass. When the conjugated diene monomer and avinyl aromatic monomer are used together, the content of the vinylaromatic monomer in the mixture is preferably within a range of 3 to 50%by mass, more preferably 4 to 45% by mass. Also, the polymerizationsystem is not particularly limited and may be a batch system or acontinuous system.

The polymerization temperature in the anionic polymerization ispreferably within a range of 0 to 150° C., more preferably 20 to 130° C.The polymerization may be carried out under a generating pressure or,preferably, at a pressure sufficient to keep the reaction monomerssubstantially in a liquid phase. When the polymerization reaction iscarried out under a pressure higher than the generating pressure, thereaction system is preferably pressurized with an inert gas. Preferably,any reaction-obstructing substances, such as water, oxygen, carbondioxide, protonic compounds, and the like are removed before beginningthe polymerization reaction.

Typically, in the rubber compositions according to the first-thirdembodiments disclosed herein, the overall composition contains 100 partsor phr (in total) of at least one rubber. In other words, the totalamount of all rubbers is considered to be 100 parts (by weight) and canalso be denoted 100 phr. Other components are added based upon 100 parts(in total) of rubber(s). As a non-limiting example, 60 parts ofstyrene-butadiene copolymer could be utilized along with 40 parts ofpolybutadiene polymer and 60 parts of silica; these amounts could bedescribed herein as 60 phr of styrene-butadiene copolymer, 40 phr ofpolybutadiene polymer and 60 phr of silica.

Reinforcing Silica Filler

As discussed above, according to the first-third embodiments disclosedherein, the rubber composition comprises about 5 to about 200 phr ofreinforcing silica filler. One or more than one reinforcing silicafiller may be utilized in the rubber compositions according to thefirst-third embodiments disclosed herein. In certain embodiments of thefirst-third embodiments disclosed herein, the total amount of the filleris 5 to 200 phr, including about 10 to about 200 phr, 10 to 200 phr,about 10 to about 175 phr, 10 to 175 phr, about 25 to about 150 phr, 25to 150 phr, about 35 to about 150 phr, 35 to 150 phr, about 25 to about125 phr, 25 to 125 phr, about 25 to about 100 phr, 25 to 100 phr, about25 to about 80 phr, 25 to 80 phr, about 35 to about 125 phr, 35 to 125phr, about 35 to about 100 phr, 35 to 100 phr, about 35 to about 80 phr,and 35 to 80 phr of at least one filler. In certain embodiments, theuseful upper range for the amount of reinforcing silica filler can beconsidered to be somewhat limited by the high viscosity imparted byfillers of this type.

As used herein, the term “reinforcing” with respect to “reinforcingcarbon black filler,” “reinforcing silica filler,” and “reinforcingfillers” generally should be understood to encompass both fillers thatare traditionally described as reinforcing as well as fillers that maybe described as semi-reinforcing. Traditionally, the term “reinforcingfiller” is used to refer to a particulate material that has a nitrogenabsorption specific surface area (N₂SA) of more than about 100 m²/g, andin certain instances more than 100 m²/g, more than about 125 m²/g, morethan 125 m²/g, or even more than about 150 m²/g or more than 150 m²/g.Alternatively, the traditional use of the term “reinforcing filler” canalso be used to refer to a particulate material that has a particle sizeof about 10 nm to about 50 nm (including 10 nm to 50 nm). Traditionally,the term “semi-reinforcing filler” is used to refer to a filler that isintermediary in either particle size, surface area (N₂SA), or both, to anon-reinforcing filler and a reinforcing filler. In certain embodimentsof the first-third embodiments disclosed herein, the term “reinforcingfiller” is used to refer to a particulate material that has a nitrogenabsorption specific surface area (N₂SA) of about 20 m²/g or greater,including 20 m²/g or greater, more than about 50 m²/g, more than 50m²/g, more than about 100 m²/g, more than 100 m²/g, more than about 125m²/g, and more than 125 m²/g. In certain embodiments of the first-thirdembodiments disclosed herein, the term “reinforcing filler” is used torefer to a particulate material that has a particle size of about 10 nmup to about 1000 nm, including 10 nm to 1000 nm, about 10 nm up to about50 nm and 10 nm to 50 nm.

Suitable reinforcing silica fillers for use in the rubber compositiondisclosed herein are well known. Non-limiting examples of reinforcingsilica fillers suitable for use in the rubber compositions of certainembodiments of the first-third embodiments disclosed herein include, butare not limited to, precipitated amorphous silica, wet silica (hydratedsilicic acid), dry silica (anhydrous silicic acid), fumed silica,calcium silicate and the like. Other suitable reinforcing silica fillersfor use in rubber compositions of certain embodiments of the first-thirdembodiments disclosed herein include, but are not limited to, aluminumsilicate, magnesium silicate (Mg₂SiO₄, MgSiO₃ etc.), magnesium calciumsilicate (CaMgSiO₄), calcium silicate (Ca₂SiO₄ etc.), aluminum silicate(Al₂SiO₅, Al₄.3SiO₄.5H₂O etc.), aluminum calcium silicate(Al₂O₃.CaO₂SiO₂, etc.), and the like. Among the listed reinforcingsilica fillers, precipitated amorphous wet-process, hydrated silicafillers are preferred. Such reinforcing silica fillers are produced by achemical reaction in water, from which they are precipitated asultrafine, spherical particles, with primary particles stronglyassociated into aggregates, which in turn combine less strongly intoagglomerates. The surface area, as measured by the BET method, is apreferred measurement for characterizing the reinforcing character ofdifferent reinforcing silica fillers. In certain embodiments of thefirst-third embodiments disclosed herein, the rubber compositioncomprises a reinforcing silica filler having a surface area (as measuredby the BET method) of about 32 m²/g to about 400 m²/g (including 32 m²/gto 400 m²/g), with the range of about 100 m²/g to about 300 m²/g(including 100 m²/g to 300 m²/g) being preferred, and the range of about150 m²/g to about 220 m²/g (including 150 m²/g to 220 m²/g) beingincluded. In certain embodiments of the first-third embodimentsdisclosed herein, the rubber composition comprises reinforcing silicafiller having a pH of about 5.5 to about 7 or slightly over 7,preferably about 5.5 to about 6.8. Some of the commercially availablereinforcing silica fillers which can be used in the rubber compositionsof certain embodiments of the first-third embodiments disclosed hereininclude, but are not limited to, Hi-Sil®190, Hi-Sil®210, Hi-Sil®215,Hi-Sil®233, Hi-Sil®243, and the like, produced by PPG Industries(Pittsburgh, Pa.). As well, a number of useful commercial grades ofdifferent reinforcing silica fillers are also available from DegussaCorporation (e.g., VN2, VN3), Rhone Poulenc (e.g., Zeosil™ 1165MP), andJ. M. Huber Corporation.

In certain embodiments of the first-third embodiments disclosed herein,as discussed in more detail below, the reinforcing silica fillercomprises a silica that has been pre-treacted with a silica couplingagent; preferably the pre-treacted silica comprises a silica that hasbeen pre-treacted with a silane-containing silica coupling agent.

Other Fillers

In certain embodiments of the first-third embodiments disclosed herein,the rubber composition further comprises one or more carbon blacks,which is commonly understood to be a reinforcing filler. In other words,carbon black is not considered to be an essential component of therubber compositions in all embodiments of the first-third embodimentsdisclosed herein. In those embodiments of the first-third embodiments,where the rubber composition includes one or more carbon blacks, thetotal amount of carbon black and reinforcing filler is about 10 to about200 phr. In certain embodiments of the first-third embodiments disclosedherein, the rubber composition comprises carbon black in an amount offrom zero to about 50% by weight of the total reinforcing filler,including zero to 50%, about 5% to about 30%, 5% to 30%, from about 5%to about 20%, 5% to 20%, about 10% to about 30%, 10% to 30%, about 10%to about 20%, and 10% to 20% by weight of the total reinforcing filler.In certain embodiments of the first-third embodiments disclosed herein,the carbon black comprises no more than about 30% by weight (includingno more than 30% by weight) of the total reinforcing filler in therubber composition. In certain embodiments of the first-thirdembodiments disclosed herein, the rubber composition comprises about 5to about 100 phr (including 5 to 100 phr) of one or more carbon blacks.Generally, suitable carbon black for use in the rubber composition ofcertain embodiments of the first-third embodiments disclosed hereinincludes any of the commonly available, commercially-produced carbonblacks, including those having a surface area of at least about 20 m²/g(including at least 20 m²/g) and, more preferably, at least about 35m²/g up to about 200 m²/g or higher (including 35 m²/g up to 200 m²/g).Surface area values used in this application are determined by ASTMD-1765 using the cetyltrimethyl-ammonium bromide (CTAB) technique. Amongthe useful carbon blacks are furnace black, channel blacks, and lampblacks. More specifically, examples of useful carbon blacks includesuper abrasion furnace (SAF) blacks, high abrasion furnace (HAF) blacks,fast extrusion furnace (FEF) blacks, fine furnace (FF) blacks,intermediate super abrasion furnace (ISAF) blacks, semi-reinforcingfurnace (SRF) blacks, medium processing channel blacks, hard processingchannel blacks and conducting channel blacks. Other carbon blacks whichcan be utilized include acetylene blacks. In certain embodiments of thefirst-third embodiments disclosed herein, the rubber compositionincludes a mixture of two or more of the foregoing blacks. Typicalsuitable carbon blacks for use in certain embodiments of the first-thirdembodiments disclosed herein are N-110, N-220, N-339, N-330, N-351,N-550, and N-660, as designated by ASTM D-1765-82a. The carbon blacksutilized can be in pelletized form or an unpelletized flocculent mass.Preferably, for more uniform mixing, unpelletized carbon black ispreferred.

In certain embodiments of the first-third embodiments, the rubbercomposition comprises at least one additional reinforcing filler inaddition to the reinforcing silica filler and the optional carbon black.Non-limiting examples of suitable additional reinforcing fillers for usein the rubber compositions of certain embodiments of the first-thirdembodiments disclosed herein include, but are not limited to, alumina,aluminum hydroxide, clay, magnesium hydroxide, boron nitride, aluminumnitride, titanium dioxide, reinforcing zinc oxide, and combinationsthereof. Suitable inorganic fillers for use in the rubber compositionsaccording to the first-third embodiments are not particularly limitedand non-limiting examples include: silica, aluminum hydroxide, talc,clay, alumina (Al₂O₃), aluminum hydrate (Al₂O₃H₂O), aluminum hydroxide(Al(OH)₃), aluminum carbonate (Al₂(CO₃)₂), aluminum nitride, aluminummagnesium oxide (MgOAl₂O₃), pyrofilite (Al₂O₃4SiO₂.H₂O), bentonite(Al₂O₃.4SiO₂.2H₂O), boron nitride, mica, kaolin, glass balloon, glassbeads, calcium oxide (CaO), calcium hydroxide (Ca(OH)₂), calciumcarbonate (CaCO₃), magnesium carbonate, magnesium hydroxide (MH(OH)₂),magnesium oxide (MgO), magnesium carbonate (MgCO₃), titanium oxide,titanium dioxide, potassium titanate, barium sulfate, zirconium oxide(ZrO₂), zirconium hydroxide [Zr(OH)₂.nH₂O], zirconium carbonate[Zr(CO₃)₂], crystalline aluminosilicates, reinforcing grades of zincoxide (i.e., reinforcing zinc oxide), and combinations thereof.

In certain embodiments of the first-third embodiments, the rubbercomposition further comprises at least one non-reinforcing filler. Incertain embodiments, the term “non-reinforcing filler” is used to referto a particulate material that has a nitrogen absorption specificsurface area (N₂SA) of less than about 20 m²/g (including less than 20m²/g), and in certain embodiments less than about 10 m²/g (includingless than 10 m²/g). The N₂SA surface area of a particulate material canbe determined according to various standard methods including ASTMD6556. In certain embodiments of the compositions and methods disclosedherein, the term “non-reinforcing filler” is used to refer to aparticulate material that has a particle size of greater than about 1000nm (including greater than 1000 nm). In certain embodiments of thefirst-third embodiments disclosed herein, the rubber composition furthercomprises at least one of the following non-reinforcing fillers: clay,graphite, titanium dioxide, magnesium dioxide, aluminum oxide, starch,boron nitride, silicon nitride, aluminum nitride, calcium silicate, andsilicon carbide.

In certain embodiments of the first-third embodiments disclosed herein,the rubber composition comprises at least one reinforcing silica filler,at least one reinforcing carbon black filler, and at least onenon-reinforcing filler, with the total amount of all reinforcing fillersbeing about 5 to about 200 phr (including 5 to 200 phr). In certainembodiments of the first-third embodiments disclosed herein, the rubbercomposition comprises at least one reinforcing silica filler, at leastone reinforcing carbon black filler, at least one additional reinforcingfiller, and at least one non-reinforcing filler, with the total amountof all reinforcing fillers being about 5 to about 200 phr (including 5to 200 phr). In certain embodiments of the first-third embodimentsdisclosed herein, the rubber composition comprises at least onereinforcing silica filler, at least one reinforcing carbon black filler,and at least one non-reinforcing filler, with the total amount of allreinforcing fillers being about 5 to about 200 phr (including 5 to 200phr). In certain embodiments of the first-third embodiments disclosedherein, the rubber composition comprises at least one reinforcing silicafiller in an amount of about 5 to about 200 phr (including 5 to 200phr), and at least one non-reinforcing filler. In certain embodiments ofthe first-third embodiments disclosed herein, the rubber compositioncomprises at least one reinforcing silica filler in an amount of about 5to about 200 phr (including 5 to 200 phr), and at least one reinforcingfiller other than carbon black or silica. In certain embodiments of thefirst-third embodiments disclosed herein, the rubber compositioncomprises at least one reinforcing silica filler, and at least onereinforcing filler other than carbon black or silica, and at least onenon-reinforcing filler, with the total amount of all reinforcing fillersbeing about 5 to about 200 phr (including 5 to 200 phr).

In certain embodiments of the first-third embodiments disclosed herein,the rubber composition further comprises cellulose ester. Celluloseester is a compound based upon cellulose (cellulose is a polysaccharidehaving the formula C₆H₁₀O₅ and consists of a linear chain of hundreds tothousands of 1,4-linked D-glucose units). Cellulose esters are producedby converting (esterifying) —OH groups in cellulose to an ester. Thehydrocarbon groups used to esterify cellulose can vary widely; incertain embodiments, the R portion of the alkanoyl group (i.e., —C(═O)R)used to esterify comprises an alkyl group having 1-10 carbons; incertain embodiments more than one type of ester group is used toesterify, thereby producing a cellulose ester with more than one type ofalkanoyl group. In certain embodiments of the first-third embodiments,the rubber composition comprises at least one cellulose ester selectedfrom cellulose acetate, cellulose acetate propionate, cellulose acetatebutyrate, cellulose acetate triacetate, cellulose tripropionate, orcellulose tributyrate. According to the first-third embodimentsdisclosed herein, the rubber composition can comprise one or more thanone cellulose ester. The cellulose ester that is utilized in the rubbercompositions of certain embodiments of the first-third embodimentsgenerally comprises a cellulose ester. Various commercially availablecellulose esters exist, including those in powder, pellet, or fiberform. Exemplary cellulose esters suitable for use in the rubbercompositions of the first-third embodiments disclosed herein includethose available from Eastman Chemical Company (Kingsport, Tenn.) such ascellulose acetate, cellulose acetate butyrate, and cellulose acetatepropionate. In certain embodiments of the first-third embodimentsdisclosed herein, the cellulose ester comprises cellulose acetate. Incertain embodiments of the first-third embodiments disclosed herein, thecellulose ester comprises cellulose acetate butyrate. In certainembodiments of the embodiments of the first-third embodiments disclosedherein, the cellulose ester comprises cellulose acetate propionate. Incertain embodiments of the first-third embodiments disclosed herein, thecellulose ester comprises cellulose acetate, cellulose acetate butyrate,cellulose acetate propionate, or a combination thereof. Cellulose esterscan be classified by various properties including the percentage ofacetylation (the converse of which is the percentage of —OH groupsremaining), melting range, Tg, and Mn. In certain embodiments of thefirst-third embodiments, the cellulose ester comprises cellulose acetatehaving at least one of the following properties: 3-4% —OH groups,melting range of 230-250° C., Tg of 180-190° C., or Mn of 30,000-50,000grams/mole (number average molecular weight in polystyrene equivalentsdetermined using size exclusion chromatography). In certain embodimentsof the first-third embodiments, the cellulose ester comprises celluloseacetate butyrate having at least one of the following properties: 1-5%—OH groups, melting range of 120-250° C., Tg of 80-170° C., or Mn of10,000 to 75,000. In certain embodiments of the first-third embodiments,the cellulose ester comprises cellulose acetate propionate having atleast one of the following properties: 1.5-5% —OH groups, melting rangeof 180-210° C., Tg of 140-160° C., and Mn of 15,000-75,000. In certainembodiments of the first-third embodiments disclosed herein, the rubbercomposition comprises cellulose ester in an amount of about 1 to about100 phr (e.g., 1 phr, 5 phr, 10 phr, 15 phr, 20 phr, 25 phr, 30 phr, 35phr, 40 phr, 45 phr, 50 phr, 55 phr, 60 phr, 65 phr, 70 phr, 75 phr, 80phr, 85 phr, 90 phr, 95 phr, 100 phr), including 1 to 100 phr, about 1to about 75 phr, 1 to 75 phr, about 5 to about 75 phr, 5 to 75 phr,about 1 to about 30 phr, 1 to 30 phr, about 5 to about 30 phr, and 5 to30 phr phr. In certain embodiments of the first-third embodimentsdisclosed herein, the rubber composition comprises cellulose ester inone of the foregoing amounts and the total amount of silica filler andcellulose ester comprises about 5 to about 200 phr, including 5 to 200phr. In certain embodiments of the first-third embodiments disclosedherein, the rubber composition comprises cellulose ester in one of theforegoing amounts, as well as carbon black filler, and the total amountof silica filler, carbon black filler and cellulose ester comprisesabout 5 to about 200 phr. In certain embodiments of the first-thirdembodiments disclosed herein, the rubber composition comprises celluloseester in one of the foregoing amounts, silica filler, optionally carbonblack filler, and at least one additional reinforcing or non-reinforcingfiller. Rubber compositions according to the first-third embodimentsdisclosed herein which include cellulose ester can be prepared accordingto various processes as discussed herein; generally according to suchprocesses the whey protein and the cellulose ester will both be addedduring a masterbatch stage. In certain embodiments, a rubber compositionaccording to the first-third embodiments disclosed herein which includescellulose ester is prepared by adding the whey protein and the celluloseester during the same masterbatch stage; in certain such embodiments,the whey protein and the cellulose ester are added during a secondmasterbatch stage and in other embodiments, the whey protein and thecellulose ester are added during a first masterbatch stage. In otherembodiments, a rubber composition according to the first-thirdembodiments disclosed herein which includes cellulose ester is preparedby adding the whey protein and the cellulose ester during differentmasterbatch stages; in certain such embodiments, the whey protein isadded before the cellulose ester (e.g., whey protein during a firstmasterbatch stage and cellulose ester during a second masterbatch stage)and in other embodiments, the whey protein is added after the celluloseester (e.g., cellulose ester during a first masterbatch stage and wheyprotein during a second masterbatch stage). Alternatively, in certainembodiments of the first-third embodiments which includes celluloseester, at least one of the whey protein and cellulose ester is addedduring more than one masterbatch stage.

In certain embodiments of the first-third embodiments disclosed herein,the rubber composition further comprises starch. Starch is apolysaccharide compound containing amylose (generally 20-25%) andamylopectin (generally 75-80%) with the relative amounts varyingsomewhat depending upon the source of the starch. Starch is generallysourced from plants with various types of plants (e.g., corn, potato,cassava, wheat, barley, rice, maize, sweet potato) providing relativelyinexpensive sources of starch. Generally, the starch will be in solidform although the particular form may vary with non-limiting examplesincluding powders, fibers, and pellets. In certain embodiments of thefirst-third embodiments disclosed herein, the rubber compositioncomprises at least one starch selected from at least one of: cornstarch, potato starch, cassava starch, wheat starch, barley starch, ricestarch, maize starch, or sweet potato starch. In certain embodiments ofthe first-third embodiments disclosed herein, the rubber compositioncomprises starch in an amount of about 1 to about 100 phr (e.g., 1 phr,5 phr, 10 phr, 15 phr, 20 phr, 25 phr, 30 phr, 35 phr, 40 phr, 45 phr,50 phr, 55 phr, 60 phr, 65 phr, 70 phr, 75 phr, 80 phr, 85 phr, 90 phr,95 phr, 100 phr), including 1 to 100 phr, about 1 to about 75 phr, 1 to75 phr, about 5 to about 75 phr, 5 to 75 phr, about 5 to about 30 phr,or 5 to 30 phr. In certain embodiments of the first-third embodimentsdisclosed herein, the rubber composition comprises starch in one of theforegoing amounts and the total amount of silica filler and starchcomprises about 5 to about 200 phr, including 5 to 200 phr. In certainembodiments of the first-third embodiments disclosed herein, the rubbercomposition comprises starch in one of the foregoing amounts, as well ascarbon black filler, and the total amount of silica filler, carbon blackfiller and starch comprises about 5 to about 200 phr. In certainembodiments of the first-third embodiments disclosed herein, the rubbercomposition comprises starch in one of the foregoing amounts, silicafiller, optionally carbon black filler, and at least one additionalreinforcing or non-reinforcing filler. Rubber compositions according tothe first-third embodiments disclosed herein which include starch can beprepared according to various processes as discussed herein; generallyaccording to such processes the whey protein and the starch will both beadded during a masterbatch stage. In certain embodiments, a rubbercomposition according to the first-third embodiments disclosed hereinwhich includes starch is prepared by adding the whey protein and thestarch during the same masterbatch stage; in certain such embodiments,the whey protein and the starch are added during a second masterbatchstage and in other embodiments, the whey protein and the starch areadded during a first masterbatch stage. In other embodiments, a rubbercomposition according to the first-third embodiments disclosed hereinwhich includes starch is prepared by adding the whey protein and thestarch during different masterbatch stages; in certain such embodiments,the whey protein is added before the starch (e.g., whey protein during afirst masterbatch stage and starch during a second masterbatch stage)and in other embodiments, the whey protein is added after the starch(e.g., starch during a first masterbatch stage and whey protein during asecond masterbatch stage). Alternatively, in certain embodiments of thefirst-third embodiments which includes starch, at least one of the wheyprotein and starch is added during more than one masterbatch stage.

Silica Coupling Agents

As discussed above, in certain embodiments of the first-thirdembodiments disclosed herein, the rubber composition includes one ormore silica coupling agents. Silica coupling agents are useful inpreventing or reducing aggregation of the silica filler in the rubbercomposition. Aggregates of the silica filler particles are believed toincrease the viscosity of the rubber composition, and, therefore,preventing this aggregation reduces the viscosity and improves theprocessibility and blending of the rubber composition.

Generally, any conventional type of silica coupling agent can be used,such as those having a silane and a constituent component or moiety thatcan react with a polymer, particularly a vulcanizable polymer. Thesilica coupling agent acts as a connecting bridge between silica and thepolymer. Suitable silica coupling agents include those containing groupssuch as alkyl alkoxy, mercapto, blocked mercapto, sulfide-containing(e.g., monosulfide-based alkoxy-containing, disulfide-basedalkoxy-containing, tetrasulfide-based alkoxy-containing), amino, vinyl,epoxy, and combinations thereof. In certain embodiments, the silicacoupling agent can be added to the rubber composition in the form of apre-treated silica; a pre-treacted silica has been pre-surface treatedwith a silane prior to being added to the rubber composition. The use ofa pre-treated silica can allow for two ingredients (i.e., silica and asilica coupling agent) to be added in one ingredient, which generallytends to make rubber compounding easier.

Alkyl alkoxysilanes have the general formula R¹ _(p)Si(OR²)_(4-p) whereeach R² is independently a monovalent organic group, and p is an integerfrom 1 to 3, with the proviso that at least one R¹ is an alkyl group.Preferably p is 1. Generally, each R¹ independently comprises C₁ to C₂₀aliphatic, C₅ to C₂₀ cycloaliphatic, or C₆ to C₂₀ aromatic; and each R²independently comprises C₁ to C₆ aliphatic. In certain exemplaryembodiments, each R¹ independently comprises C₆ to C₁₅ aliphatic and inadditional embodiments each R¹ independently comprises C₈ to C₁₄aliphatic. Mercapto silanes have the general formula HS—R³—Si(R⁴)(R⁵)₂where R³ is a divalent organic group, R⁴ is a halogen atom or an alkoxygroup, each R⁵ is independently a halogen, an alkoxy group or amonovalent organic group. The halogen is chlorine, bromine, fluorine, oriodine. The alkoxy group preferably has 1-3 carbon atoms. Blockedmercapto silanes have the general formula B—S—R⁶—Si—X₃ with an availablesilyl group for reaction with silica in a silica-silane reaction and ablocking group B that replaces the mercapto hydrogen atom to block thereaction of the sulfur atom with the polymer. In the foregoing generalformula, B is a block group which can be in the form of an unsaturatedheteroatom or carbon bound directly to sulfur via a single bond; R⁶ isC₁ to C₆ linear or branched alkylidene and each X is independentlyselected from the group consisting of C₁ to C₄ alkyl or C₁ to C₄ alkoxy.

Non-limiting examples of alkyl alkoxysilanes suitable for use in therubber compositions of certain exemplary embodiments according to thefirst-third embodiments disclosed herein include, but are not limitedto, octyltriethoxysilane, octyltrimethoxysilane, trimethylethoxysilane,cyclohexyltriethoxysilane, isobutyltriethoxy-silane,ethyltrimethoxysilane, cyclohexyl-tributoxysilane,dimethyldiethoxysilane, methyltriethoxysilane, propyltriethoxysilane,hexyltriethoxysilane, heptyltriethoxysilane, nonyltriethoxysilane,decyltriethoxysilane, dodecyltriethoxysilane, tetradecyltriethoxysilane,octadecyltriethoxysilane, methyloctyldiethoxysilane,dimethyldimethoxysilane, methyltrimethoxysilane, propyltrimethoxysilane,hexyltrimethoxysilane, heptyltrimethoxysilane, nonyltrimethoxysilane,decyltrimethoxysilane, dodecyltrimethoxysilane,tetradecyltrimethoxysilane, octadecyl-trimethoxysilane, methyloctyldimethoxysilane, and mixtures thereof.

Non-limiting examples of bis(trialkoxysilylorgano)polysulfides suitablefor use in the rubber compositions of certain exemplary embodimentsaccording to the first-third embodiments disclosed herein includebis(trialkoxysilylorgano) disulfides andbis(trialkoxysilylorgano)tetrasulfides. Specific non-limiting examplesof bis(trialkoxysilylorgano)disulfides suitable for use in the rubbercompositions of certain exemplary embodiments according to thefirst-third embodiments disclosed herein include, but are not limitedto, 3,3′-bis(triethoxysilylpropyl) disulfide,3,3′-bis(trimethoxysilylpropyl)disulfide,3,3′-bis(tributoxysilylpropyl)disulfide,3,3′-bis(tri-t-butoxysilylpropyl)disulfide,3,3′-bis(trihexoxysilylpropyl)disulfide,2,2′-bis(dimethylmethoxysilylethyl)disulfide,3,3′-bis(diphenylcyclohexoxysilylpropyl)disulfide,3,3′-bis(ethyl-di-sec-butoxysilylpropyl)disulfide,3,3′-bis(propyldiethoxysilylpropyl)disulfide, 12,12′-bis(triisopropoxysilylpropyl)disulfide,3,3′-bis(dimethoxyphenylsilyl-2-methylpropyl)disulfide, and mixturesthereof. Non-limiting examples of bis(trialkoxysilylorgano)tetrasulfidesilica coupling agents suitable for use in the rubber compositions ofcertain exemplary embodiments according to the first-third embodimentsdisclosed herein include, but are not limited to,bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasufide, bis(3-trimethoxysilylpropyl)tetrasulfide,3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide,2-triethoxysilyl-N,N-dimethylthiocarbamoyl tetrasulfide,3-trimethoxysilylpropyl-benzothiazole tetrasulfide,3-triethoxysilylpropylbenzothiazole tetrasulfide, and mixtures thereof.Bis(3-triethoxysilylpropyl)tetrasulfide is sold commercially as Si69® byEvonik Degussa Corporation.

Non-limiting examples of mercapto silanes suitable for use in the rubbercompositions of certain exemplary embodiments of the first-thirdembodiments disclosed herein include, but are not limited to,1-mercaptomethyltriethoxysilane, 2-mercaptoethyltriethoxysilane,3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldiethoxysilane,2-mercaptoethyltripropoxysilane,18-mercaptooctadecyldiethoxychlorosilane, and mixtures thereof.

Non-limiting examples of blocked mercapto silanes suitable for use inthe rubber compositions of certain exemplary embodiments according tothe first-third embodiments disclosed herein include, but are notlimited to, those described in U.S. Pat. Nos. 6,127,468; 6,204,339;6,528,673; 6,635,700; 6,649,684; and 6,683,135, the disclosures of whichare hereby incorporated by reference. Representative examples of theblocked mercapto silanes for use herein in certain exemplary embodimentsdisclosed herein include, but are not limited to,2-triethoxysilyl-1-ethylthioacetate;2-trimethoxysilyl-1-ethylthioacetate;2-(methyldimethoxysilyl)-1-ethylthioacetate;3-trimethoxysilyl-1-propylthioacetate; triethoxysilylmethyl-thioacetate;trimethoxysilylmethylthioacetate; triisopropoxysilylmethylthioacetate;methyldiethoxysilylmethylthioacetate;methyldimethoxysilylmethylthioacetate;methyldiisopropoxysilylmethylthioacetate;dimethylethoxysilylmethylthioacetate;dimethylmethoxysilylmethylthioacetate;dimethylisopropoxysilylmethylthioacetate;2-triisopropoxysilyl-1-ethylthioacetate;2-(methyldiethoxysilyl)-1-ethylthioacetate,2-(methyldiisopropoxysilyl)-1-ethylthioacetate;2-(dimethylethoxysilyl-1-ethylthioacetate;2-(dimethylmethoxysilyl)-1-ethylthioacetate;2-(dimethylisopropoxysilyl)-1-ethylthioacetate;3-triethoxysilyl-1-propylthioacetate;3-triisopropoxysilyl-1-propylthioacetate;3-methyldiethoxysilyl-1-propyl-thioacetate;3-methyldimethoxysilyl-1-propylthioacetate;3-methyldiisopropoxysilyl-1-propylthioacetate;1-(2-triethoxysilyl-1-ethyl)-4-thioacetylcyclohexane;1-(2-triethoxysilyl-1-ethyl)-3-thioacetylcyclohexane;2-triethoxysilyl-5-thioacetylnorbornene;2-triethoxysilyl-4-thioacetylnorbornene;2-(2-triethoxysilyl-1-ethyl)-5-thioacetylnorbornene;2-(2-triethoxy-silyl-1-ethyl)-4-thioacetylnorbornene;1-(1-oxo-2-thia-5-triethoxysilylphenyl)benzoic acid;6-triethoxysilyl-1-hexylthioacetate;1-triethoxysilyl-5-hexylthioacetate;8-triethoxysilyl-1-octylthioacetate;1-triethoxysilyl-7-octylthioacetate;6-triethoxysilyl-1-hexylthioacetate;1-triethoxysilyl-5-octylthioacetate;8-trimethoxysilyl-1-octylthioacetate;1-trimethoxysilyl-7-octylthioacetate;10-triethoxysilyl-1-decylthioacetate;1-triethoxysilyl-9-decylthioacetate;1-triethoxysilyl-2-butylthioacetate;1-triethoxysilyl-3-butylthioacetate;1-triethoxysilyl-3-methyl-2-butylthioacetate;1-triethoxysilyl-3-methyl-3-butylthioacetate;3-trimethoxysilyl-1-propylthiooctanoate;3-triethoxysilyl-1-propyl-1-propylthiopalmitate;3-triethoxysilyl-1-propylthiooctanoate;3-triethoxysilyl-1-propylthiobenzoate;3-triethoxysilyl-1-propylthio-2-ethylhexanoate;3-methyldiacetoxysilyl-1-propylthioacetate;3-triacetoxysilyl-1-propylthioacetate;2-methyldiacetoxysilyl-1-ethylthioacetate;2-triacetoxysilyl-1-ethylthioacetate;1-methyldiacetoxysilyl-1-ethylthioacetate;1-triacetoxysilyl-1-ethyl-thioacetate;tris-(3-triethoxysilyl-1-propyl)trithiophosphate;bis-(3-triethoxysilyl-1-propyl)methyldithiophosphonate;bis-(3-triethoxysilyl-1-propyl)ethyldithiophosphonate;3-triethoxysilyl-1-propyldimethylthiophosphinate;3-triethoxysilyl-1-propyldiethylthiophosphinate;tris-(3-triethoxysilyl-1-propyl)tetrathiophosphate;bis-(3-triethoxysilyl-1 propyl)methyltrithiophosphonate;bis-(3-triethoxysilyl-1-propyl)ethyltrithiophosphonate;3-triethoxysilyl-1-propyldimethyldithiophosphinate;3-triethoxysilyl-1-propyldiethyldithiophosphinate;tris-(3-methyldimethoxysilyl-1-propyl)trithiophosphate;bis-(3-methyldimethoxysilyl-1-propyl)methyldithiophosphonate;bis-(3-methyldimethoxysilyl-1-propyl)-ethyldithiophosphonate;3-methyldimethoxysilyl-1-propyldimethylthiophosphinate;3-methyldimethoxysilyl-1-propyldiethylthiophosphinate;3-triethoxysilyl-1-propylmethylthiosulfate;3-triethoxysilyl-1-propylmethanethiosulfonate;3-triethoxysilyl-1-propylethanethiosulfonate;3-triethoxysilyl-1-propylbenzenethiosulfonate;3-triethoxysilyl-1-propyltoluenethiosulfonate;3-triethoxysilyl-1-propylnaphthalenethiosulfonate;3-triethoxysilyl-1-propylxylenethiosulfonate;triethoxysilylmethylmethylthiosulfate;triethoxysilylmethylmethanethiosulfonate;triethoxysilylmethylethanethiosulfonate;triethoxysilylmethylbenzenethiosulfonate;triethoxysilylmethyltoluenethiosulfonate;triethoxysilylmethylnaphthalenethiosulfonate;triethoxysilylmethylxylenethiosulfonate, and the like. Mixtures ofvarious blocked mercapto silanes can be used. A further example of asuitable blocked mercapto silane for use in certain exemplaryembodiments is NXT™ silane (3-octanoylthio-1-propyltriethoxysilane),commercially available from Momentive Performance Materials Inc. ofAlbany, N.Y.

Non-limiting examples of pre-treated silicas (i.e., silicas that havebeen pre-surface treated with a silane) suitable for use in the rubbercompositions of certain exemplary embodiments according to thefirst-third embodiments disclosed herein include, but are not limitedto, Ciptane® 255 LD and Ciptane® LP (PPG Industries) silicas that havebeen pre-treated with a mercaptosilane, and Coupsil® 8113 (Degussa) thatis the product of the reaction between organosilaneBis(triethoxysilylpropyl) polysulfide (Si69) and Ultrasil® VN3 silica.Coupsil 6508, Agilon 400™ silica from PPG Industries, Agilon 454® silicafrom PPG Industries, and 458® silica from PPG Industries. In thoseembodiments of the rubber compositions and methods disclosed hereinwhere the silica comprises a pre-treated silica, the pre-treated silicais used in an amount as previously disclosed for the reinforcing silicafiller (i.e., about 5 to about 200 phr, including 5 to 200 phr, about 10to about 200 phr, 10 to 200 phr, about 10 to about 175 phr, 10 to 175phr, about 25 to about 150 phr, 25 to 150 phr, about 35 to about 150phr, 35 to 150 phr, about 25 to about 125 phr, 25 to 125 phr, about 25to about 100 phr, 25 to 100 phr, about 25 to about 80 phr, 25 to 80 phr,about 35 to about 125 phr, 35 to 125 phr, about 35 to about 100 phr, 35to 100 phr, about 35 to about 80 phr, and 35 to 80 phr about 5 to about200 phr, including about 25 to about 150 phr, about 35 to about 150 phr,about 25 to about 125 phr, about 25 to about 100 phr, about 25 to about80 phr, about 35 to about 125 phr, about 35 to about 100 phr, and about35 to about 80 phr).

The amount of silica coupling agent used in the rubber compositionsaccording to the first-third embodiments disclosed herein may vary. Incertain embodiments of the first-third embodiments disclosed herein, therubber compositions do not contain any silica coupling agent. In otherembodiments of the first-third embodiments disclosed herein, the silicacoupling agent is present in an amount sufficient to provide a ratio ofthe total amount of silica coupling agent to reinforcing silica fillerof about 1:100 to about 1:5 (i.e., about 0.01 to about 20 parts byweight per 100 parts of silica), including 1:100 to 1:5, about 1:100 toabout 1:10, 1:100 to 1:10, about 1:100 to about 1:20, 1:100 to 1:20,about 1:100 to about 1:25, and 1:100 to 1:25 as well as about 1:100 toabout 0:100 and 1:100 to 0:100. In certain embodiments according to thefirst-third embodiments disclosed herein, the rubber compositioncomprises about 0.01 to about 10 phr silica coupling agent, including0.01 to 10 phr, about 0.01 to about 5 phr, 0.01 to 5 phr, about 0.01 toabout 3 phr, and 0.01 to 3 phr.

Other Components of Rubber Composition

In certain embodiments of the first-third embodiments, the rubbercomposition includes (i.e., further comprises) a cure package.Generally, the cure package includes at least one of: a vulcanizingagent; a vulcanizing accelerator; a vulcanizing activator (e.g., zincoxide, stearic acid, and the like); a vulcanizing inhibitor, and ananti-scorching agent. In certain embodiments, the cure package includesat least one vulcanizing agent, at least one vulcanizing accelerator, atleast one vulcanizing activator and optionally a vulcanizing inhibitorand/or an anti-scorching agent. Vulcanizing accelerators and vulcanizingactivators act as catalysts for the vulcanization agent. Vulcanizinginhibitors and anti-scorching agents are known in the art and can beselected by one skilled in the art based on the vulcanizate propertiesdesired.

Examples of suitable types of vulcanizing agents for use in the rubbercompositions according to certain embodiments of the first-thirdembodiments, include but are not limited to, sulfur or peroxide-basedcuring components. Thus, in certain such embodiments, the curativecomponent includes a sulfur-based curative or a peroxide-based curative.Examples of specific suitable sulfur vulcanizing agents include“rubbermaker's” soluble sulfur; sulfur donating curing agents, such asan amine disulfide, polymeric polysulfide, or sulfur olefin adducts; andinsoluble polymeric sulfur. Preferably, the sulfur vulcanizing agent issoluble sulfur or a mixture of soluble and insoluble polymeric sulfur.For a general disclosure of suitable vulcanizing agents and othercomponents used in curing, e.g., vulcanizing inhibitor andanti-scorching agents, one can refer to Kirk-Othmer, Encyclopedia ofChemical Technology, 3rd ed., Wiley Interscience, N.Y. 1982, Vol. 20,pp. 365 to 468, particularly Vulcanization Agents and AuxiliaryMaterials, pp. 390 to 402, or Vulcanization by A. Y. Coran, Encyclopediaof Polymer Science and Engineering, Second Edition (1989 John Wiley &Sons, Inc.), both of which are incorporated herein by reference.Vulcanizing agents can be used alone or in combination. Generally, thevulcanizing agents are used in an amount ranging from 0.1 to 10 phr,including from 1 to 7.5 phr, including from 1 to 5 phr, and preferablyfrom 1 to 3.5 phr.

Vulcanizing accelerators are used to control the time and/or temperaturerequired for vulcanization and to improve properties of the vulcanizate.Examples of suitable vulcanizing accelerators for use in the rubbercompositions according to certain embodiments of the first-thirdembodiments disclosed herein include, but are not limited to, thiazolevulcanization accelerators, such as 2-mercaptobenzothiazole,2,2′-dithiobis(benzothiazole) (MBTS),N-cyclohexyl-2-benzothiazole-sulfenamide (CBS),N-tert-butyl-2-benzothiazole-sulfenamide (TBBS), and the like; guanidinevulcanization accelerators, such as diphenyl guanidine (DPG) and thelike; thiuram vulcanizing accelerators; carbamate vulcanizingaccelerators; and the like. Generally, the amount of the vulcanizationaccelerator used ranges from 0.1 to 10 phr, preferably 0.5 to 5 phr.

Vulcanizing activators are additives used to support vulcanization.Generally vulcanizing activators include both an inorganic and organiccomponent. Zinc oxide is the most widely used inorganic vulcanizationactivator. Various organic vulcanization activators are commonly usedincluding stearic acid, palmitic acid, lauric acid, and zinc salts ofeach of the foregoing. Generally, the amount of vulcanization activatorused ranges from 0.1 to 6 phr, preferably 0.5 to 4 phr.

Vulcanization inhibitors are used to control the vulcanization processand generally retard or inhibit vulcanization until the desired timeand/or temperature is reached. Common vulcanization inhibitors include,but are not limited to, PVI (cyclohexylthiophthalmide) from Santogard.Generally, the amount of vulcanization inhibitor is 0.1 to 3 phr,preferably 0.5 to 2 phr.

Other ingredients that may be employed in the rubber compositions ofcertain embodiments of the first-third embodiments disclosed herein arewell known to those of skill in the art and include oils (processing andextender), waxes, processing aids, antioxidants, tackifying resins,reinforcing resins, peptizers, and one or more additional rubbers.

Various types of processing and extender oils may be utilized,including, but not limited to aromatic, naphthenic, and low PCA oils.Suitable low PCA oils include those having a polycyclic aromatic contentof less than 3 percent by weight as determined by the IP346 method.Procedures for the IP346 method may be found in Standard Methods forAnalysis & Testing of Petroleum and Related Products and BritishStandard 2000 Parts, 2003, 62nd edition, published by the Institute ofPetroleum, United Kingdom. Suitable low PCA oils include mild extractionsolvates (MES), treated distillate aromatic extracts (TDAE), TRAE, andheavy naphthenics. Suitable MES oils are available commercially asCATENEX SNR from SHELL, PROREX 15, and FLEXON 683 from EXXONMOBIL,VIVATEC 200 from BP, PLAXOLENE MS from TOTAL FINA ELF, TUDALEN 4160/4225from DAHLEKE, MES-H from REPSOL, MES from Z8, and OLIO MES S201 fromAGIP. Suitable TDAE oils are available as TYREX 20 from EXXONMOBIL,VIVATEC 500, VIVATEC 180, and ENERTHENE 1849 from BP, and EXTENSOIL 1996from REPSOL. Suitable heavy naphthenic oils are available as SHELLFLEX794, ERGON BLACK OIL, ERGON H2000, CROSS C2000, CROSS C2400, and SANJOAQUIN 2000L. Suitable low PCA oils also include various plant-sourcedoils such as can be harvested from vegetables, nuts, and seeds.Non-limiting examples include, but are not limited to, soy or soybeanoil, sunflower oil, safflower oil, corn oil, linseed oil, cotton seedoil, rapeseed oil, cashew oil, sesame oil, camellia oil, jojoba oil,macadamia nut oil, coconut oil, and palm oil. The foregoing processingoils can also be used as an extender oil, i.e., to prepare anoil-extended polymer or copolymer. Generally, for most applications thetotal amount of oil used (processing oil and extender oil) in the rubbercompositions and methods disclosed herein ranges about 1 to about 70phr, including 1 to 70 phr, about 2 to about 60 phr, about 2 to about 60phr, about 3 to about 50 phr, and 3 to 50 phr. However, in certainapplications, the total amount of oil used (processing oil and extenderoil) in the rubber compositions and methods disclosed herein is muchhigher and ranges up to about 175 phr, including up to 175 phr, up toabout 150 phr, up to 150 phr, up to about 100 phr, and up to 100 phr.

Various antioxidants are known to those of skill in the art and may beutilized in the rubber compositions of certain embodiments of thefirst-fourth embodiments; these include but are not limited to phenolicantioxidants, amine phenol antioxidants, hydroquinone antioxidants,alkyldiamine antioxidants, and amine compound antioxidants such asN-phenyl-N′-isopropyl-p-phenylenediamine (IPPD), orN-(1,3-dimethylbutyl)-N′-phenyl-phenylenediamine (6PPD). One or morethan one type as well as one or more than one of each type may beutilized in certain embodiments of the first-third embodiments. Incertain embodiments of the first-third embodiments, the total amount ofantioxidant(s) used is 0.1 to 6 phr

Viscosity Reduction in Rubber Compositions

As discussed above, the third embodiment disclosed herein is a methodfor reducing the viscosity of a silica-filler-containing rubbercomposition. The method comprises the use of a rubber compositioncomprising at least one rubber, about 5 to 200 phr (including 5 to 200phr) of a reinforcing silica filler, and a whey protein component in anamount sufficient to provide about 0.1 to about 10 phr (including 0.1 to10 phr) of whey protein. The reduction in viscosity from the use of wheyprotein should also be understood to occur in the rubber compositions ofthe first and second embodiments disclosed herein.

In certain embodiments according to the first-third embodiment, thereduction in viscosity from the use of about 0.1 to about 10 phr of wheyprotein is at least about 5% (as compared to a rubber compositioncontaining the same ingredients except for lacking any whey protein). Incertain embodiments according to the first-third embodiment, thereduction in viscosity from the use of 0.1 to 10 phr of whey protein isat least 5% (as compared to a rubber composition containing the sameingredients except for lacking any whey protein). In certain embodimentsaccording to the first-embodiment, the rubber composition contains nosilica coupling agent and the reduction in viscosity from the use ofabout 0.1 to about 10 phr of whey protein is at least about 10%,including at least about 20%, and in certain such embodiments at leastabout 30%, about 10% to about 50%, about 10% to about 45%, about 20% toabout 50% and about 20% to about 45% (as compared to a rubbercomposition containing the same ingredients except for lacking any wheyprotein). In certain embodiments according to the first-embodiment, therubber composition contains no silica coupling agent and the reductionin viscosity from the use of 0.1 to 10 phr of whey protein is at least10%, including at least 20%, and in certain such embodiments at least30%, 10% to 50%, 10% to 45%, 20% to 50% and 20% to 45% (as compared to arubber composition containing the same ingredients except for lackingany whey protein).

Generally, the useful upper range for the amount of silica filler inrubber compositions can be considered to be somewhat limited by the highviscosity imparted to the rubber composition by fillers of this type. Itis believed that silica filler particles tend to aggregate in the rubbercomposition, and aggregates of the silica filler particles thencontribute to increased viscosity of the rubber composition. Rubbercompositions with high viscosity are more difficult to process, and highviscosity makes it more difficult to homogeneously blend the variouscomponents in the rubber composition. It is therefore desirable to addprocessing aids to the rubber composition to prevent aggregation of thesilica particles, reduce the viscosity, and improve the processibilityand blending of the rubber composition.

As discussed above, silica coupling agents typically have been added torubber compositions to prevent aggregation of the silica fillerparticles and reduce the viscosity of the rubber composition. However,silica coupling agents have limitations. First, they are expensive, andtherefore add to the cost of manufacturing rubber compositions and thetires or tire components made from these rubber compositions. Because ofthe expense, rubber manufacturers are interested in minimizing theamount of silica coupling agents in rubber compositions. Second, certainsilica coupling agents may release volatile organic compounds (e.g.,methanol, ethanol, or propanol) when they are incorporated into rubbercompositions which can be undesirable.

Unexpectedly, it has been discovered that when whey protein is used in arubber composition comprising a reinforcing silica filler, the viscosityof the rubber composition is reduced and the rubber composition can beprocessed more easily. This reduction in viscosity of the rubbercomposition occurs even when the amount of the silica coupling agentused in the rubber composition is less than about 8% of the amount ofsilica (i.e., less than 8 parts silica coupling agent to 100 parts ofreinforcing silica filler), e.g., from about 0 to about 4% of the amountof silica. Thus, by including whey protein in the rubber composition,the amount of silica coupling agent can be reduced to less than theamount of silica coupling agent typically used in rubber compositionscomprising reinforcing silica filler. The resulting rubber compositionshave comparable processibility and physical properties when comparedwith typical rubber compositions with higher amounts of silica couplingagent.

Methods for Preparing Rubber Compositions

Also disclosed herein are methods for preparing rubber compositions. Therubber compositions according to the first-third embodiments disclosedherein may generally be formed by mixing together the ingredients forthe rubber composition (as disclosed above) by methods known in the art,such as, for example, by kneading the ingredients together in a Banburymixer or on a milled roll. The methods generally include at least onenon-productive master-batch mixing stage and a final productive mixingstage. The term non-productive master-batch stage is known to those ofskill in the art and generally understood to be a mixing stage where novulcanizing agents or vulcanization accelerators are added. The termfinal productive mixing stage is also known to those of skill in the artand generally understood to be the mixing stage where the vulcanizingagents and vulcanization accelerators are added into the rubbercomposition. In certain embodiments of the compositions and methodsdisclosed herein, more than one non-productive master-batch mixing stagemay be used. In certain embodiments of the compositions and methodsdisclosed herein, more than one non-productive master-batch mixing stageis used and the whey protein component is added in the first (initial)master-batch stage. In other embodiments of the compositions and methodsdisclosed herein, at least two non-productive master-batch mixing stagesare used and the whey protein component is added in the secondmaster-batch stage. In yet other embodiments of the compositions andmethods disclosed herein, more than one non-productive master-batchmixing stage is used and the whey protein component is added in the lastnon-productive master-batch mixing stage.

In certain embodiments of the methods for preparing rubber compositionsaccording to the first-third embodiments disclosed herein, thenon-productive master batch mixing stage(s) may be conducted at atemperature of about 130° C. to about 200° C. In certain embodiments,the final productive mixing stage may be conducted at a temperaturebelow the vulcanization temperature in order to avoid unwanted pre-cureof the rubber composition. Therefore, the temperature of the productivemixing stage should not exceed about 120° C. and is typically about 40°C. to about 120° C., or about 60° C. to about 110° C. and, especially,about 75° C. to about 100° C.

In certain embodiments of the first-third embodiments disclosed herein,a rubber composition is prepared according to a method that includes atleast one non-productive mixing stage and at least one productivemixture stage. In certain embodiments, the method for preparing therubber compositions of the present disclosure includes: (1) mixing, inat least one non-productive master-batch stage, a rubber compositioncomprising: 100 phr of at least one rubber; from about 5 to about 200phr (including 5 to 200 phr) of reinforcing silica filler; and a wheyprotein component in an amount sufficient to provide about 0.1 to about10 phr whey (including 0.1 to 10 phr) protein; and (2) mixing theresulting product of the non-productive master batch in a finalproductive stage along with at least one curative, such as a curativepackage, as discussed above. With respect to certain embodiments of thefirst embodiment disclosed herein, the list of ingredients should beunderstood as including ingredients to be mixed to form the rubbercomposition. Accordingly, in such embodiments, the whey protein is addedvia a whey protein component which usually is not 100% whey protein.With respect to the certain embodiments of the second embodimentdisclosed herein (i.e., a rubber composition that has been subjected tocuring), the list of ingredients should be understood to comprise theingredients present in the cured rubber composition such that the amountof whey protein can be measured without regard to its particular source(e.g., without regard to the particular whey protein component used toprovide the whey protein).

In certain embodiments of the first-third embodiments disclosed herein,a rubber composition is prepared according to a method that includes atleast one non-productive mixing stage and at least one productive mixingstage. In certain embodiments of the first-third embodiments disclosedherein, the method for preparing the rubber compositions of the presentdisclosure includes: (1) mixing, in at least one non-productivemaster-batch stage, a rubber composition comprising: 100 phr of at leastone rubber; from about 5 to about 200 phr (including 5 to 200 phr) ofreinforcing silica filler; a whey protein component in an amountsufficient to provide about 0.1 to about 10 phr (including 0.1 to 10phr) whey protein; and about 0.5 to about 20 phr (including 0.5 to 20phr) of a silica coupling agent; and (2) mixing the resulting product ofthe non-productive master batch in a final productive stage along withat least one curative, such as a cure package, as discussed above. Incertain such embodiments, the silica coupling agent is used in an amountsuch that the weight ratio of the silica coupling agent to reinforcingsilica filler is about 1:100 to about 1:20 (including 1:100 to 1:20).

As previously discussed, certain embodiments disclosed herein includetires, tire treads, and tire sidewalls comprising a rubber compositionof the first-third embodiments as otherwise disclosed herein, i.e.,comprising at least one rubber, about 5 to about 200 phr (including 5 to200 phr) of a reinforcing silica filler, and a whey protein component inan amount sufficient to provide about 0.1 to about 10 phr (including 0.1to 10 phr) whey protein (or when referring to a cured rubbercomposition, about 0.1 to about 10 phr of whey protein (including 0.1 to10 phr of whey protein)). More specifically, the present disclosureincludes a tire comprising a rubber composition of the first-thirdembodiments as otherwise disclosed herein, a tire comprising a tiretread comprising a rubber composition of the first-third embodiments asotherwise disclosed herein, a tire tread comprising a rubber compositionof the first-third embodiments as otherwise disclosed herein, a tirecomprising a tire sidewall comprising a rubber composition of thefirst-third embodiments as otherwise disclosed herein, and a tiresidewall comprising a rubber composition of the first-third embodimentsas otherwise disclosed herein. Generally, when the rubber compositionsof the first-third embodiments disclosed herein are utilized in tires,tire treads, or tire sidewalls, these compositions are processed intotire components according to ordinary tire manufacturing techniquesincluding standard rubber shaping, molding, and curing techniques. Anyof the various rubber tire components can be fabricated including, butnot limited to, treads, sidewalls, belt skims, and carcass. Typically,vulcanization of a tire component is effected by heating thevulcanizable composition in a mold; e.g., it may be heated to about 140°C. to about 180° C. Cured or crosslinked rubber compositions may bereferred to as vulcanizates, which generally contain three-dimensionalpolymeric networks that are thermoset. The other ingredients, such asprocessing aides and fillers, may be evenly dispersed throughout thevulcanized network. In certain embodiments, pneumatic tires containingthe rubber compositions as disclosed herein can be produced as discussedin U.S. Pat. Nos. 5,866,171, 5,876,527, 5,931,211, and 5,971,046, whichare incorporated herein by reference.

Examples

The following examples illustrate specific and exemplary embodimentsand/or features of the embodiments of the present disclosure. Theexamples are provided solely for the purposes of illustration and shouldnot be construed as limitations of the present disclosure. Numerousvariations over these specific examples are possible without departingfrom the spirit and scope of the presently disclosed embodiments. Itshould specifically be understood that the whey protein utilized in theexamples (both type and amount) can be utilized with rubbers, fillers,and other ingredients which differ in amount, composition, or both fromthose used in the examples (i.e., as fully disclosed in the precedingparagraphs). Moreover, whey protein can be utilized in amounts and fromsources that differ from those provided in the examples (i.e., as fullydisclosed in the preceding paragraphs).

In Examples 1-9, rubber compositions containing reinforcing silicafiller were prepared using various rubbers along with varying amounts ofwhey protein and silica coupling agent. Example 1 utilizes naturalrubber in combination with polybutadiene, Example 2 utilizes syntheticpolyisoprene rubber in combination with polybutadiene, Example 3utilizes polybutadiene in combination with natural rubber, Example 4utilizes styrene-butadiene rubber in combination with natural rubber,Example 5 utilizes a relatively higher surface area silica (as comparedto Examples 1-4) with natural rubber, Example 6 utilizes a mercaptosilane in combination with natural rubber and polybutadiene, Example 7utilizes a pre-reacted silica with natural rubber and styrene-butadienerubber, Example 8 utilizes alternative whey protein components (sweetwhey or whey protein isolate) in combination with natural rubber andpolybutadiene, and Example 9 utilizes natural rubber and polybutadienewith varying placement of the whey protein component. The rubbercompositions were prepared in a four stage mixing process (i.e., twomaster-batch stages, remilling, and final batch) according to theformulations shown in Tables 1A-6A. The amount of each ingredient usedis reported as parts per hundred rubber (phr). The mixing process usedfor these formulations is outlined in Table 1B below. The whey proteincomponent utilized in Examples 1-7 and 9 was acid whey (containingapproximately 12 weight % protein). For Example 8, the sweet wheycontained approximately 12 weight % protein, the whey protein isolatecontained approximately 92 weight % protein and the acid whey was thesame as used in Examples 1-6 and 8 (i.e., containing approximately 12weight % protein).

After curing, each of the rubber compositions was tested for tensileproperties. The results testing of the formulations of Tables 1A-9A areshown in Tables 1D-9D, below. The abbreviation Eb is used for elongationat break and Tb for stress at break, which measurements provide anindication of a rubber composition's tear resistance, which isparticularly relevant when it is incorporated into a tire tread. Theabbreviation M300 is used for tensile stress at 300% elongation. Theabbreviation E′ is used for dynamic storage modulus, which provides ameasure of the hardness of the rubber composition; steering stability ona dry road surface (dry performance) is generally impacted by E′ withhigher values preferred. The index values listed in Tables 1D-9D weredetermined by comparing the value for the formulation according to thepresent disclosure with the respective value for the control (i.e.,dividing the test value by the control value).

Tensile mechanical properties of the samples were determined followingthe guidelines, but not restricted to, the standard procedure describedin ASTM D-412, using dumbbell-shaped samples with a cross-sectiondimension of 4 mm in width and 1.9 mm in thickness at the center.Specimens were strained at a constant rate and the resulting force wasrecorded as a function of extension (strain). Force readings are shownin the Tables below as engineering-stresses by reference to the originalcross-sectional area of the test piece. The specimens were tested at 25°C. unless indicated to the contrary. Samples were cured for 40 minutesat 150° C.

The dynamic storage modulus (E′) and tan δ values were measured with adynamic mechanical thermal spectrometer (Eplexor® 500N from GaboQualimeter Testanlagen GmbH of Ahiden, Germany) under the followingconditions: measurement mode: tensile test mode, measuring frequency: 52Hz, applying 0.2% strain from 50 to −5° C. and 1% strain from −5 to 65°C., measuring temperatures (as indicated in Table IC below), sampleshape: 4.75 mm wide×29 mm long×2.0 mm thick. A rubber composition's tanδ at 0° C. is indicative of its wet traction when incorporated into atire tread, its tan δ at 30° C. is indicative of its dry traction whenincorporated into a tire tread and its tan δ at 60° C. is indicative ofits rolling resistance when incorporated into a tire tread.

The MH and ML values were measured using a moving die cure Monsantorheometer MDR 2000 from Alpha Technologies at 160° C., following theguidelines of, but not restricted to, ASTM-D 2084. Measurements were inkg-cm prior to preparing index values. MH represents maximum torque andML represents minimum torque.

The viscosities disclosed herein are real dynamic viscosities determinedusing an Alpha Technologies RPA (Rubber Process Analyzer) instrumentwhich is rotorless. Measurements were made following the guidance of,but not strictly according to ASTM D 6204. In accordance with ASTM D6204, a three point frequency sweep was conducted. The rubbercompositions were pre-heated for 1 minute at 130° C. In accordance withthe ASTM procedure, strain sweep was conducted at 130° C., strain at 100percent, and 1 Hz were conducted. The viscosity data reported is from arun conducted at 266° F., G′ at 0.2 minutes.

TABLE 1A Rubber Formulations Based on Natural Rubber Sample # 1-1* 1-21-3 1-4* 1-5 1-6 1-7* 1-8 1-9 Master-Batch #1 Natural rubber 50 50 50 5050 50 50 50 50 Polybutadiene¹ 50 50 50 50 50 50 50 50 50 Silica filler²56 56 56 56 56 56 56 56 56 Silica coupling agent³ 0 0 0 2.24 2.24 2.244.48 4.48 4.48 Silica coupling agent 0 0 0 4 4 4 8 8 8 (% based onamount of silica) Whey protein 0 5 10 0 5 10 0 5 10 component (acidwhey) Whey protein (from 0 0.6 1.2 0 0.6 1.2 0 0.6 1.2 WPC) Processingoil 10 10 10 10 10 10 10 10 10 Antioxidant #1 1.5 1.5 1.5 1.5 1.5 1.51.5 1.5 1.5 Vulcanization 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 activator#1 Master-Batch #2 Carbon black 10 10 10 10 10 10 10 10 10 Antioxidant#2 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 Final BatchVulcanization 2 2 2 2 2 2 2 2 2 activator #2 Vulcanizing agent 2.1 2.12.1 2.1 2.1 2.1 2.1 2.1 2.1 (sulfur) Vulcanization 1.65 1.65 1.65 1.651.65 1.65 1.65 1.65 1.65 accelerators ¹High-cis polybutadiene (cis-bondcontent 96%) ²commercially available silica filler having a surface area(N₂SA) of about 190-210 m²/g ³commercially available silica couplingagent of the trialkoxy disulfide type(bis(triethoxysilylpropyl)disulfide) *denotes control (with respectivetest values listed to the right of each control)

TABLE 1B Mixing Parameters for silica-containing compositions Stage TimeCondition Master-Batch 0 seconds Charge polymers Stage 1 (initial 30seconds  Charge any oil, silica filler and other master-batch temp: 105°C., ingredients, increase rotor to 75 rpm rotor rpm started Drop basedon max temperature of 310° F. (154° C.) at 60) Master-Batch 0 secondsCharge additional ingredients listed under Master- Stage 2 (initialBatch #2 temp: 105° C., Drop based on max temperature of 300° F. (149°C.) rotor rpm started at 60) Remill Stage 0 seconds Charge Master Batchfrom #2 (initial temp: Drop based on max temperature of 300° F. (149°C.) 105° C., rotor rpm at 60) Final Batch 0 seconds Charge Remill Stage(initial 0 seconds Charge curatives temp: 80° C., Drop based on maxtemperature of 210° F. (99° C.) rotor rpm at 40)

TABLE 2A Rubber Formulations Based on Synthetic Polyisoprene RubberSample # 2-1* 2-2 2-3 2-4* 2-5 2-6 2-7* 2-8 2-9 Master-Batch #1Polyisoprene 80 80 80 80 80 80 80 80 80 Polybutadiene¹ 20 20 20 20 20 2020 20 20 Silica filler² 56 56 56 56 56 56 56 56 56 Silica couplingagent³ 0 0 0 2.24 2.24 2.24 4.48 4.48 4.48 Silica coupling agent 0 0 0 44 4 8 8 8 (% based on amount of silica) Whey protein 0 5 10 0 5 10 0 510 component (acid whey) Whey protein (from 0 0.6 1.2 0 0.6 1.2 0 0.61.2 WPC) Processing oil 10 10 10 10 10 10 10 10 10 Antioxidant #1 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 1.5 Master-Batch #2 Carbon black 10 10 10 10 10 10 10 10 10Antioxidant #2 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 Final BatchVulcanization 2 2 2 2 2 2 2 2 2 activator (Zinc oxide) Vulcanizing agent2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 (sulfur) Vulcanization 1.65 1.651.65 1.65 1.65 1.65 1.65 1.65 1.65 accelerators ¹High-cis polybutadiene(cis-bond content 96%) ²commercially available silica filler having asurface area (N₂SA) of about 190-210 m²/g ³commercially available silicacoupling agent of the trialkoxy disulfidetype(bis(triethoxysilylpropyl)disulfide) *denotes control (withrespective test values listed to the right of each control)

TABLE 3A Rubber Formulations Based on Polybutadiene Sample # 3-1* 3-23-3 3-4* 3-5 3-6 3-7* 3-8 3-9 Master-Batch #1 Polybutadiene¹ 80 80 80 8080 80 80 80 80 Natural rubber 20 20 20 20 20 20 20 20 20 Silica filler²56 56 56 56 56 56 56 56 56 Silica coupling agent³ 0 0 0 2.24 2.24 2.244.48 4.48 4.48 Silica coupling agent 0 0 0 4 4 4 8 8 8 (% based onamount of silica) Whey protein 0 5 10 0 5 10 0 5 10 component (acidwhey) Whey protein (from 0 0.6 1.2 0 0.6 1.2 0 0.6 1.2 WPC) Processingoil 10 10 10 10 10 10 10 10 10 Antioxidant #1 1.5 1.5 1.5 1.5 1.5 1.51.5 1.5 1.5 Stearic acid 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5Master-Batch #2 Carbon black 10 10 10 10 10 10 10 10 10 Antioxidant #20.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 Final Batch Vulcanization 22 2 2 2 2 2 2 2 activator (Zinc oxide) Vulcanizing agent 2.1 2.1 2.1 2.12.1 2.1 2.1 2.1 2.1 (sulfur) Vulcanization 1.65 1.65 1.65 1.65 1.65 1.651.65 1.65 1.65 accelerators ¹High-cis polybutadiene (cis-bond content96%) ²commercially available silica filler having a surface area (N₂SA)of about 190-210 m²/g ³commercially available silica coupling agent ofthe trialkoxy disulfide type (bis(triethoxysilylpropyl)disulfide)*denotes control (with respective test values listed to the right ofeach control)

TABLE 4A Rubber Formulations Based on Styrene-Butadiene Rubber Sample #4-1* 4-2 4-3 4-4* 4-5 4-6 4-7* 4-8 4-9 Master-Batch #1 Styrene-butadiene80 80 80 80 80 80 80 80 80 copolymer¹ Natural rubber 20 20 20 20 20 2020 20 20 Silica filler² 56 56 56 56 56 56 56 56 56 Silica couplingagent³ 0 0 0 2.24 2.24 2.24 4.48 4.48 4.48 Silica coupling agent 0 0 0 44 4 8 8 8 (% based on amount of silica) Whey protein 0 5 10 0 5 10 0 510 component (acid whey) Whey protein (from 0 0.6 1.2 0 0.6 1.2 0 0.61.2 WPC) Processing oil 10 10 10 10 10 10 10 10 10 Antioxidant #1 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 1.5 Master-Batch #2 Carbon black 10 10 10 10 10 10 10 10 10Antioxidant #2 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 Final BatchVulcanization 2 2 2 2 2 2 2 2 2 activator (Zinc oxide) Vulcanizing agent2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 (sulfur) Vulcanization 1.65 1.651.65 1.65 1.65 1.65 1.65 1.65 1.65 accelerators ¹Styrene-butadienerubber (tin coupled, with 17% cis, 25% trans, 58% vinyl, 20% styrene, Tgof −33° C. Tg, 405,000 Mw, 250,000 Mn) ²commercially available silicafiller having a surface area (N₂SA) of about 190-210 m²/g ³commerciallyavailable silica coupling agent of the trialkoxy disulfide type(bis(triethoxysilylpropyl)disulfide) *denotes control (with respectivetest values listed to the right of each control)

TABLE 5A Rubber Formulations Containing High Surface Area Silica Sample# 5-1* 5-2 5-3 5-4* 5-5 5-6 5-7* 5-8 5-9 Master-Batch #1 Natural rubber80 80 80 80 80 80 80 80 80 Polybutadiene¹ 20 20 20 20 20 20 20 20 20Silica filler² 56 56 56 56 56 56 56 56 56 Silica coupling agent³ 0 0 02.24 2.24 2.24 4.48 4.48 4.48 Silica coupling agent 0 0 0 4 4 4 8 8 8 (%based on amount of silica) Whey protein 0 5 10 0 5 10 0 5 10 component(acid whey) Whey protein (from 0 0.6 1.2 0 0.6 1.2 0 0.6 1.2 WPC)Processing oil 10 10 10 10 10 10 10 10 10 Antioxidant #1 1.5 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 Stearic acid 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5Master-Batch #2 Carbon black 10 10 10 10 10 10 10 10 10 Antioxidant #20.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 Final Batch Vulcanization 22 2 2 2 2 2 2 2 activator (Zinc oxide) Vulcanizing agent 2.1 2.1 2.1 2.12.1 2.1 2.1 2.1 2.1 (sulfur) Vulcanization 1.65 1.65 1.65 1.65 1.65 1.651.65 1.65 1.65 accelerators ¹High-cis polybutadiene (cis-bond content96%) ²commercially available silica filler having a surface area (N₂SA)of about 270-305 m²/g ³commercially available silica coupling agent ofthe trialkoxy disulfide type (bis(triethoxysilylpropyl)disulfide)*denotes control (with respective test values listed to the right ofeach control)

TABLE 6A Rubber Formulations Containing Silica and Mercapto SilaneSample # 6-1* 6-2 6-3 6-4* 6-5 6-6 6-7* 6-8 6-9 Master-Batch #1 Naturalrubber 80 80 80 80 80 80 80 80 80 Polybutadiene¹ 20 20 20 20 20 20 20 2020 Silica filler² 56 56 56 56 56 56 56 56 56 Silica coupling agent³ 0 00 2.24 2.24 2.24 4.48 4.48 4.48 Silica coupling agent 0 0 0 4 4 4 8 8 8(% based on amount of silica) Whey protein 0 5 10 0 5 10 0 5 10component (acid whey) Whey protein (from 0 0.6 1.2 0 0.6 1.2 0 0.6 1.2WPC) Processing oil 10 10 10 10 10 10 10 10 10 Antioxidant #1 1.5 1.51.5 1.5 1.5 1.5 1.5 1.5 1.5 Stearic acid 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 Master-Batch #2 Carbon black 10 10 10 10 10 10 10 10 10 Antioxidant#2 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 Final BatchVulcanization 2 2 2 2 2 2 2 2 2 activator (Zinc oxide) Vulcanizing agent2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 (sulfur) Vulcanization 1.65 1.651.65 1.65 1.65 1.65 1.65 1.65 1.65 accelerators ¹High-cis polybutadiene(cis-bond content 96%) ²commercially available silica filler having asurface area (N₂SA) of about 190-210 m²/g ³commercially availablemercapto-group containing silica coupling agent *denotes control (withrespective test values listed to the right of each control)

TABLE 7A Rubber Formulations Containing Pre-reacted Silane Sample # 7-1*7-2 7-3 7-4* 7-5 7-6 Master-Batch #1 Natural rubber 10 10 10 10 10 10Styrene-butadiene 123.75 123.75 123.75 123.75 123.75 123.75 rubber¹Pre-reacted silica² 56 56 56 80 80 80 Whey protein 0 5 10 0 5 10component (acid whey) Whey protein (from 0 0.6 1.2 0 0.6 1.2 WPC)Processing oil 1.9 1.9 1.9 1.9 1.9 1.9 Antioxidant #1 1.5 1.5 1.5 1.51.5 1.5 Stearic acid 1.5 1.5 1.5 1.5 1.5 1.5 Master-Batch #2 Carbonblack 10 10 10 10 10 10 Antioxidant #2 0.95 0.95 0.95 0.95 0.95 0.95Final Batch Vulcanization activator 2 2 2 2 2 2 (Zinc oxide) Vulcanizingagent 2.1 2.1 2.1 2.1 2.1 2.1 (sulfur) Vulcanization 3.6 3.6 3.6 3.6 3.63.6 accelerators ¹Styrene-butadiene rubber (containing 40.5% styrene),oil-extended with 37.5 phr oil ²Commercially available silicapre-treated with mercaptosilane *denotes control (with respective testvalues listed to the right of each control)

TABLE 8A Rubber Formulations Containing Varying Whey Protein ComponentsSample # 8-1* 8-2 8-3 8-4 Master-Batch #1 Natural rubber 80 80 80 80Polybutadiene¹ 20 20 20 20 Silica filler² 56 56 56 56 Silica couplingagent³ 2.24 2.24 2.24 2.24 Whey protein component (acid 0 5 0 0 whey)Whey protein component (sweet 0 0 5 0 whey) Whey protein component (whey0 0 0 5 protein isolate) Whey protein (from WPC) 0 0.6 0.6 0.9Processing oil 10 10 10 10 Antioxidant #1 1.5 1.5 1.5 1.5 Stearic acid1.5 1.5 1.5 1.5 Master-Batch #2 Carbon black 10 10 10 10 Antioxidant #20.95 0.95 0.95 0.95 Final Batch Vulcanization activator (Zinc 2 2 2 2oxide) Vulcanizing agent (sulfur) 2.1 2.1 2.1 2.1 Vulcanizationaccelerators 1.65 1.65 1.65 1.65 ¹High-cis polybutadiene (cis-bondcontent 96%) ²commercially available silica filler having a surface area(N₂SA) of about 190-210 m²/g ³commercially available mercapto-groupcontaining silica coupling agent *denotes control (with respective testvalues listed to the right of each control)

TABLE 9A Rubber Formulations With Varying Placement of Whey ProteinSample # 9-1* 9-2 9-3 Master-Batch #1 Natural rubber 80 80 80Polybutadiene¹ 20 20 20 Silica filler² 56 56 56 Silica coupling agent³2.24 2.24 2.24 Silica coupling agent (% based on 4 4 4 amount of silica)Whey protein component (acid whey) 0 10 0 Whey protein (from WPC) 0 1.20 Processing oil 10 10 10 Antioxidant #1 1.5 1.5 1.5 Stearic acid 1.51.5 1.5 Master-Batch #2 Carbon black 10 10 10 Whey protein component(acid whey) 0 0 10 Whey protein (from WPC) 0 0 1.2 Antioxidant #2 0.950.95 0.95 Final Batch Vulcanization activator (Zinc oxide) 2 2 2Vulcanizing agent (sulfur) 2.1 2.1 2.1 Vulcanization accelerators 1.651.65 1.65 ¹High-cis polybutadiene (cis-bond content 96%) ²commerciallyavailable silica filler having a surface area (N₂SA) of about 190-210m²/g ³commercially available mercapto-group containing silica couplingagent *denotes control (with respective test values listed to the rightof each control)

TABLE 1D 1-3, 1-9, 1-1, 1-2, 0% 1-4, 1-5, 1-7, 1-8, 8% 0% 0% silane, 4%4% 1-6, 4% 8% 8% silane, silane, silane, 10 silane, silane, silane,Silane, silane, 10 0 phr 5 phr phr 0 phr 5 phr 10 phr 0 phr 5 phr phrProperty WPC WPC WPC WPC WPC WPC WPC WPC WPC Indexed 1.00 0.87 0.81 1.000.83 0.73 M300 Indexed — — — 1.00 0.76 0.66 1.00 0.80 0.63 Tb Indexed —— — 1.00 0.94 0.94 1.00 1.02 0.93 Eb Indexed — — — 1.00 1.14 1.18 1.001.04 1.12 tan δ 0° C. Indexed — — — 1.00 1.17 1.00 1.00 1.10 1.19 tan δ30° C. Indexed — — — 1.00 1.00 0.94 1.00 1.06 0.95 E′ 30° C. Indexed — —— 1.00 1.12 1.24 1.00 1.22 1.28 tan δ 60° C. RPA 132 86 75 100 78 71 8169 66 viscosity Indexed 1.00 0.65 0.57 1.00 0.78 0.71 1.00 0.85 0.81viscosity — measurement not obtained

TABLE 2D 2-3, 2-6, 2-9, 2-1, 2-2, 0% 2-4, 2-5, 4% 2-7, 2-8, 8% 0% 0%silane, 4% 4% silane, 8% 8% silane, silane, 0 silane, 10 silane, silane,10 Silane, silane, 5 10 phr 5 phr phr 0 phr 5 phr phr 0 phr phr phrProperty WPC WPC WPC WPC WPC WPC WPC WPC WPC Indexed M300 1.00 0.80 0.901.00 0.87 0.81 1.00 0.84 0.73 Indexed Tb 1.00 0.83 0.69 1.00 0.73 0.621.00 0.78 0.65 Indexed Eb 1.00 1.08 0.93 1.00 0.92 0.89 1.00 1.00 0.98Indexed tan δ 0° C. 1.00 1.10 1.05 1.00 1.20 1.20 1.00 1.07 1.05 Indexedtan δ 30° C. 1.00 1.09 1.15 1.00 1.15 1.23 1.00 1.10 1.16 Indexed E′ 30°C. 1.00 1.09 1.33 1.00 0.87 1.05 1.00 1.06 1.10 Indexed tan δ 60° C.1.00 1.08 1.21 1.00 1.17 1.30 1.00 1.19 1.28 RPA viscosity 117 86 77 9770 67 70 62 62 Indexed viscosity 1.00 0.74 0.66 1.00 0.72 0.69 1.00 0.890.89

TABLE 3D 3-3, 3-6, 3-9, 3-1, 3-2, 0% 3-4, 3-5, 4% 3-7, 3-8, 8% 0% 0%silane, 4% 4% silane, 8% 8% silane, silane, silane, 10 silane, silane,10 Silane, silane, 10 0 phr 5 phr phr 0 phr 5 phr phr 0 phr 5 phr phrProperty WPC WPC WPC WPC WPC WPC WPC WPC WPC Indexed M300 1.00 0.67 0.621.00 0.57 0.61 1.00 0.61 0.61 Indexed Tb 1.00 1.25 1.00 1.00 0.99 0.881.00 0.78 0.64 Indexed Eb 1.00 1.67 1.59 1.00 1.48 1.35 1.00 1.28 1.14Indexed tan δ 0° C. 1.00 1.18 1.23 1.00 1.32 1.33 1.00 1.28 1.24 Indexedtan δ 1.00 1.18 1.27 1.00 1.33 1.37 1.00 1.30 1.30 30° C. Indexed E′ 30°C. 1.00 0.82 1.10 1.00 0.63 0.76 1.00 0.77 0.77 Indexed tan δ 1.00 1.231.36 1.00 1.35 1.45 1.00 1.35 1.40 60° C. RPA viscosity 133 87 76 114 8274 93 67 66 Indexed viscosity 1.00 0.65 0.57 1.00 0.72 0.65 1.00 0.720.71

TABLE 4D 4-3, 4-1, 4-2, 0% 4-4, 4-5, 4-6, 4-7, 4-8, 4-9, 0% 0% silane,4% 4% 4% 8% 8% 8% silane, silane, 10 silane, silane, silane, Silane,silane, silane, 0 phr 5 phr phr 0 phr 5 phr 10 phr 0 phr 5 phr 10 phrProperty WPC WPC WPC WPC WPC WPC WPC WPC WPC Indexed 1.00 0.69 0.61 1.000.72 0.74 1.00 0.80 0.74 M300 Indexed Tb 1.00 0.98 1.02 1.00 1.44 1.221.00 1.01 0.90 Indexed Eb 1.00 1.38 1.57 1.00 1.73 1.45 1.00 1.13 1.13Indexed tan 1.00 1.05 1.12 1.00 1.23 1.35 1.00 1.10 1.09 δ 0° C. Indexedtan 1.00 1.14 1.25 1.00 1.12 1.11 1.00 0.92 0.97 δ 30° C. Indexed E′1.00 0.92 0.87 1.00 0.63 0.49 1.00 0.74 0.84 30° C. Indexed tan 1.001.15 1.28 1.00 1.11 1.02 1.00 0.94 1.01 δ 60° C. RPA 120 91 73 102 80 7279 83 75 viscosity Indexed 1.00 0.76 0.61 1.00 0.78 0.71 1.00 1.05 0.95viscosity

TABLE 5D 5-3, 5-6, 5-1, 5-2, 0% 5-4, 5-5, 4% 5-7, 5-8, 5-9, 0% 0%silane, 4% 4% silane, 8% 8% 8% silane, 0 silane, 10 silane, silane, 10Silane, silane, 5 silane, phr 5 phr phr 0 phr 5 phr phr 0 phr phr 10 phrProperty WPC WPC WPC WPC WPC WPC WPC WPC WPC Indexed M300 1.00 0.99 1.021.00 1.00 0.90 1.00 1.0 0.90 Indexed Tb 1.00 0.83 0.69 1.00 0.73 0.621.00 0.78 0.65 Indexed Eb 1.00 0.92 0.91 1.00 0.97 0.94 1.00 0.93 0.91Indexed tan δ 0° C. 1.00 1.24 1.30 1.00 1.22 1.28 1.00 1.11 1.14 Indexedtan δ 30° C. 1.00 1.19 1.26 1.00 1.19 1.23 1.00 1.04 1.12 Indexed E′ 30°C. 1.00 0.76 0.86 1.00 0.75 0.70 1.00 0.69 0.87 Indexed tan δ 60° C.1.00 1.23 1.39 1.00 1.23 1.31 1.00 1.08 1.18 RPA viscosity 111 86 72 10376 66 84 68 65 Indexed viscosity 1.00 0.77 0.65 1.00 0.74 0.64 1.00 0.810.77

TABLE 6D 6-3, 6-6, 6-9, 6-1, 6-2, 0% 6-4, 6-5, 4% 6-7, 6-8, 8% 0% 0%silane, 4% 4% silane, 8% 8% silane, silane, 0 silane, 10 silane, silane,10 Silane, silane, 5 10 phr 5 phr phr 0 phr 5 phr phr 0 phr phr phrProperty WPC WPC WPC WPC WPC WPC WPC WPC WPC Indexed M300 — — — 1.000.96 0.87 1.00 0.95 0.76 Indexed Tb — — — 1.00 0.86 0.74 1.00 0.94 0.76Indexed Eb — — — 1.00 0.99 0.98 1.00 1.00 1.02 Indexed tan δ 0° C. 1.001.15 1.30 1.00 1.19 1.18 1.00 1.03 1.05 Indexed tan δ 30° C. 1.00 1.141.24 1.00 1.08 1.15 1.00 0.97 1.04 Indexed E′ 30° C. 1.00 0.92 0.76 1.000.64 0.76 1.00 0.86 1.06 Indexed tan δ 60° C. 1.00 1.18 1.36 1.00 1.121.28 1.00 1.02 1.16 RPA viscosity 98 78 75 78 68 64 61 60 59 Indexedviscosity 1.00 0.80 0.77 1.00 0.87 0.82 1.00 0.98 0.97 — measurement notobtained

TABLE 7D 7-1, 56 7-2, 56 7-3, 56 7-4, 80 7-5, 80 7-6, 80 phr PT phr PTphr PT phr PT phr PT phr PT silica, 0 silica, 5 silica, 10 silia, 0silica, 5 silica, 10 phr phr phr phr phr phr Property WPC WPC WPC WPCWPC WPC Indexed M300 — — — — — — Indexed Tb — — — — — — Indexed Eb — — —— — — Indexed tan δ 0° C. 1.00 0.94 0.91 1.00 0.92 0.84 Indexed tan δ30° C. 1.00 1.03 1.00 1.00 1.03 1.03 Indexed E′ 30° C. 1.00 1.03 1.391.00 1.18 1.40 Indexed tan δ 60° C. 1.00 1.36 1.29 1.00 1.29 1.35 RPAviscosity 63 58 56 64 62 57 Indexed viscosity 1.00 0.92 0.89 1.00 0.970.89 — measurement not obtained

TABLE 8D Property 8-1 8-2 8-3 8-4 Indexed M300 1.00 0.89 0.91 1.09Indexed Tb 1.00 0.77 0.88 1.00 Indexed Eb 1.00 0.99 0.97 0.96 Indexedtan δ 0° C. 1.00 1.04 1.09 1.00 Indexed tan δ 30° C. 1.00 1.00 1.05 1.00Indexed E′ 30° C. 1.00 0.96 0.98 1.10 Indexed tan δ 60° C. 1.00 1.061.11 1.00 RPA viscosity 73 65 69 64 Indexed viscosity 1.00 0.89 0.950.88

TABLE 9D 9-1, no 9-2, WPC 9-3, WPC Property WPC 1st MB 2nd MB IndexedM300 1.00 0.77 0.69 Indexed Tb 1.00 0.78 0.77 Indexed Eb 1.00 0.98 1.04Indexed tan δ 0° C. 1.00 1.24 1.10 Indexed tan δ 30° C. 1.00 1.31 1.25Indexed E′ 30° C. 1.00 0.79 1.15 Indexed tan δ 60° C. 1.00 1.33 1.33 RPAviscosity 87 84 77 Indexed viscosity 1.00 0.97 0.89

As is apparent from a review of the data in Tables 1D to 9D, theaddition of whey protein results in rubber compositions with reducedviscosity. Lower viscosity results in improved processibility for therubber composition. As would be expected, at 0% whey protein, theviscosity of each rubber composition is reduced as the amount of silicacoupling agent increases. Surprisingly, though, as whey protein is addedto the rubber compositions, the viscosities of the low-silanecompositions approach the viscosity of the high-silane composition. At awhey protein component concentration of 10 phr (1.2 phr whey protein),the rubber composition with 0% silane has essentially the same viscosityas the rubber composition with 4% silane. The rubber compositions with10 phr whey protein component and either 0% or 4% silane have lowerviscosities than the composition with 0 phr whey protein component and8% silane, and these rubber compositions are only slightly more viscousthan the rubber composition containing 10 phr whey protein component and8% silane.

Examples 10 and 11

In Examples 10 and 11, rubber compositions containing reinforcing silicafiller were prepared using various rubbers along with varying amounts ofwhey protein and either cellulose ester or starch filler. Example 10utilizes natural rubber in combination with polybutadiene for the rubbercomponent and Example 11 utilizes styrene-butadiene rubber incombination with polybutadiene for the rubber component. Moreover, inExample 10 the whey protein, cellulose ester, or both were added eitherin the first master batch or in the second master batch. The rubbercompositions were prepared in a four stage mixing process (i.e., twomaster-batch stages, remilling, and final batch) according to theformulations shown in Tables 10A-11A. The amount of each ingredient usedis reported as parts per hundred rubber (phr). The mixing process usedfor these formulations is outlined in Table 1B above. The whey proteincomponent utilized in Examples 10 and 11 was acid whey (containingapproximately 12 weight % protein). In Example 11, the whey protein,starch or both were added in the second master batch.

TABLE 10A Rubber Formulations Containing Silica and Cellulose EsterSample # 10-1* 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 Master-Batch #1Natural rubber 80 80 80 80 80 80 80 80 80 Polybutadiene¹ 20 20 20 20 2020 20 20 20 Silica filler² 56 56 56 56 56 56 56 56 56 Silica couplingagent³ 2.24 2.24 2.24 2.24 2.24 2.24 2.24 2.24 2.24 Silica couplingagent (% 4 4 4 4 4 4 4 4 4 based on amount of silica) Whey proteincomponent 0 10 0 10 10 0 0 0 0 (acid whey) Whey protein (from WPC) 0 1.20 1.2 1.2 0 0 0 0 Cellulose ester⁴ 5 0 5 5 0 0 0 0 5 Processing oil 1010 10 10 10 10 10 10 10 Antioxidant #1 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 Stearic acid 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Master-Batch #2Carbon black 10 10 10 10 0 10 10 10 10 Whey protein component 0 0 0 0 010 0 10 10 (acid whey) Whey protein (from WPC) 0 0 0 0 0 1.2 0 1.2 1.2Cellulose ester⁴ 0 0 0 0 5 0 5 5 0 Antioxidant #2 0.95 0.95 0.95 0.950.95 0.95 0.95 0.95 0.95 Final Batch Vulcanization activator 2 2 2 2 2 22 2 2 (Zinc oxide) Vulcanizing agent (sulfur) 2.1 2.1 2.1 2.1 2.1 2.12.1 2.1 2.1 Vulcanization accelerators 1.65 1.65 1.65 1.65 1.65 1.651.65 1.65 1.65 ¹High-cis polybutadiene (cis-bond content 96%)²commercially available silica filler having a surface area (N₂SA) ofabout 190-210 m²/g ³commercially available trialkoxydisulfide type(bis(triethoxysilylpropyl)disulfide) silica coupling agent ⁴Celluloseacetate butyrate from Eastman ™ Chemical Company (product number CAB381). *denotes control

TABLE 11A Rubber Formulations Containing Silica and Starch Sample #11-1* 11-2 11-3 11-4 Master-Batch #1 Natural rubber 80 80 80 80Polybutadiene¹ 20 20 20 20 Silica filler² 56 56 56 56 Silica couplingagent³ 4.48 4.48 4.48 4.48 Silica coupling agent (% based on 8 8 8 8amount of silica) Processing oil 10 10 10 10 Antioxidant #1 1.5 1.5 1.51.5 Stearic acid 1.5 1.5 1.5 1.5 Master-Batch #2 Carbon black 10 10 1010 Whey protein component (acid whey) 0 5 0 5 Whey protein (from WPC) 00.6 0 0.6 Starch⁴ 0 0 15 15 Final Batch Vulcanization activator (Zincoxide) 2 2 2 2 Vulcanizing agent (sulfur) 2.1 2.1 2.1 2.1 Vulcanizationaccelerators 1.65 1.65 1.65 1.65 ¹High-cis polybutadiene (cis-bondcontent 96%) ²commercially available silica filler having a surface area(N₂SA) of about 190-210 m²/g ³commercially available(bis(triethoxysilylpropyl)disulfide) silica coupling agent ⁴Potatostarch from Hoogwegt U.S., Inc. (Lake Forest, Illinois) *denotes control

After curing, each of the rubber compositions was tested for variousproperties according to the procedures described above for Examples 1-9.Results are reported in Tables 10D and 11D below. The index valueslisted in Tables 10D-11D were determined by comparing the value for theformulation according to the present disclosure with the respectivevalue for the control (i.e., dividing the test value by the controlvalue).

TABLE 10D Property 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 IndexedM300 1.00 0.77 0.93 0.68 0.69 0.97 0.54 0.60 0.61 Indexed Tb 1.00 0.780.88 0.69 0.77 1.06 0.61 0.61 0.46 Indexed Eb 1.00 0.98 0.97 1.06 1.041.09 1.11 0.98 0.83 Indexed tan δ 0° C. 1.00 1.25 1.11 1.32 1.12 1.131.19 1.29 1.26 Indexed tan δ 30° C. 1.00 1.28 1.12 1.37 1.23 1.11 1.311.34 1.37 Indexed E′ 30° C. 1.00 0.79 0.91 0.87 1.15 0.99 1.14 0.82 0.84Indexed tan δ 60° C. 1.00 1.35 1.16 1.45 1.35 1.11 1.46 1.45 1.49 RPAviscosity 87.3 84.0 92.4 74.4 77.0 84.3 73.8 75.0 78.9 Indexed viscosity1.00 0.96 1.06 0.85 0.88 0.97 0.85 0.86 0.90

TABLE 11D Property 11-1 11-2 11-3 11-4 Indexed M300 1.00 0.83 1.01 0.91Indexed Tb 1.00 0.73 0.88 0.72 Indexed Eb 1.00 0.92 0.92 0.89 Indexedtan δ 0° C. 1.00 1.01 1.00 1.01 Indexed tan δ 30° C. 1.00 1.08 1.01 1.07Indexed E′ 30° C. 1.00 1.14 1.11 1.16 Indexed tan δ 60° C. 1.00 1.131.00 1.14 Indexed ML 1.00 0.77 1.14 0.84 Indexed MH 1.00 0.80 1.04 0.82Indexed ΔM 1.00 0.80 0.99 0.81 RPA viscosity 80.1 71.6 78.9 74.7 Indexedviscosity 1.00 0.89 0.98 0.93

As can be seen from the data in Table 10D, the addition of celluloseester alone (i.e., without any whey protein) in Examples 10-3 and 10-7resulted in a decrease in viscosity when the cellulose ester was addedin the second masterbatch stage but an increase in viscosity when thecellulose ester was added in the first masterbatch stage, both ascompared to the control Example 10-1. The addition of whey protein alone(i.e., without any cellulose ester) in Examples 10-2 and 10-6 resultedin a decrease in viscosity as compared to the control Example 10-1. Theaddition of whey protein together with cellulose ester in Examples 10-4,10-5, 10-8, and 10-9 also resulted in a decrease in viscosity ascompared to the control Example 10-1; the magnitude of the decrease inviscosity depended upon the masterbatch stage in which each was addedwith relatively larger decreases occurring when whey protein andcellulose ester were added together (either in the first or secondmasterbatch stage). For the combined addition of whey protein andcellulose ester, the smallest decrease in viscosity occurred when wheyprotein was added in the second masterbatch stage and cellulose ester inthe first masterbatch stage (Example 10-9). For the combined addition ofwhey protein and cellulose ester, the addition of whey protein in thefirst masterbatch (Examples 10-4 and 10-5) resulted in an increase in Ebas compared to the control Example 10-1 and as compared to the combinedaddition of whey protein and cellulose ester with the addition of wheyprotein the second masterbatch (Examples 10-8 and 10-9); the increase inEb was not dependent upon when the cellulose ester was added. Theaddition of whey protein alone (Examples 10-2 and 10-6) withoutcellulose ester resulted in an increase or decrease in Tb depending uponwhether the whey protein was added in the first or second masterbatch.

As can be seen from the data in Table 11D, the use of starch without anywhey protein (Example 11-3) resulted in a slight decrease in viscosityas compared to the control (Example 11-1). The use of whey proteinwithout any starch (Example 11-2) resulted in a decrease in viscosity ascompared to the control (consistent with the data in Tables 1D-9D, asdiscussed above). The combined use of whey protein and starch (Example11-4) resulted in a decrease in viscosity as compared to the controlExample (11-1), although the decrease was less than that obtained by theuse of whey protein alone (i.e., without any starch).

This application discloses several numerical range limitations thatsupport any range within the disclosed numerical ranges, even though aprecise range limitation is not stated verbatim in the specification,because the embodiments of the compositions and methods disclosed hereincould be practiced throughout the disclosed numerical ranges. Withrespect to the use of substantially any plural or singular terms herein,those having skill in the art can translate from the plural to thesingular or from the singular to the plural as is appropriate to thecontext or application. The various singular or plural permutations maybe expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims are generallyintended as “open” terms. For example, the term “including” should beinterpreted as “including but not limited to,” the term “having” shouldbe interpreted as “having at least,” the term “includes” should beinterpreted as “includes but is not limited to.” It will be furtherunderstood by those within the art that if a specific number of anintroduced claim recitation is intended, such an intent will beexplicitly recited in the claim, and in the absence of such recitationno such intent is present. For example, as an aid to understanding, thefollowing appended claims may contain usage of the introductory phrases“at least one” and “one or more” to introduce claim recitations.However, the use of such phrases should not be construed to imply thatthe introduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation to inventions containing only one such recitation, even whenthe same claim includes the introductory phrases “one or more” or “atleast one” and indefinite articles such as “a” or “an” (e.g., “a” or“an” should typically be interpreted to mean “at least one” or “one ormore”); the same holds true for the use of definite articles used tointroduce claim recitations. In addition, even if a specific number ofan introduced claim recitation is explicitly recited, those skilled inthe art will recognize that such recitation should typically beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, typicallymeans at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, and C”would include but not be limited to systems that have A alone, B alone,C alone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word or phrase presenting two ormore alternative terms, whether in the description, claims, or drawings,should be understood to contemplate the possibilities of including oneof the terms, either of the terms, or both terms. For example, thephrase “A or B” will be understood to include the possibilities of “A”or “B” or “A and B.”

All references, including but not limited to patents, patentapplications, and non-patent literature are hereby incorporated byreference herein in their entirety.

While various aspects and embodiments of the compositions and methodshave been disclosed herein, other aspects and embodiments will beapparent to those skilled in the art. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting, with the true scope and spirit beingindicated by the claims.

What is claimed is: 1-25. (canceled)
 26. A rubber compositioncomprising: a. at least one rubber; b. reinforcing silica filler in anamount of about 5 to about 200 phr; and c. a whey protein component inan amount sufficient to provide about 0.1 to about 10 phr whey protein.27. The rubber composition of claim 26, wherein the whey proteincomponent is in an amount sufficient to provide about 0.5 to about 5 phrwhey protein.
 28. The rubber composition of claim 26, wherein the wheyprotein component comprises at least one of acid whey powder, reducedlactose whey, reduced minerals whey, sweet whey powder, whey proteinconcentrate, and whey protein isolate.
 29. A rubber composition that hasbeen subjected to curing, the rubber composition comprising: a. at leastone rubber; b. reinforcing silica filler in an amount of about 5 toabout 200 phr; c. whey protein in an amount of about 0.1 to about 10phr; and d. a cure package.
 30. The rubber composition of claim 29,wherein the amount of whey protein comprises about 0.5 to about 5 phr.31. The rubber composition according to claim 29, wherein the wheyprotein meets at least one of the following: a. a majority of theprotein chains in the whey protein have a molecular weight of greaterthan about 10 kDaltons; b. a majority of the proteins in the wheyprotein are a combination of alpha-lactalbumin and beta-lactoglobulin;or c. a degree of hydrolysis of less than 50%.
 32. The rubbercomposition according to claim 29, wherein the composition furthercomprises cellulose ester.
 33. The rubber composition according to claim29, wherein the composition further comprises starch.
 34. The rubbercomposition according to claim 29, wherein the reinforcing silica fillercomprises pre-treated silica.
 35. The rubber composition according toclaim 29, further comprising about 0.5 to about 20 phr silica couplingagent, wherein the ratio of the total amount of silica coupling agent tosilica comprises about 1:100 to about 1:5.
 36. The rubber compositionaccording to claim 29, wherein at least a majority (by weight) of the atleast one rubber comprises at least one of: natural rubber, polyisoprenerubber, polybutadiene rubber, and styrene-butadiene rubber.
 37. A tiretread or sidewall comprising the rubber composition of claim
 29. 38. Atire containing at least one component comprising the rubber compositionof claim
 29. 39. A method for reducing the viscosity of a silicafiller-containing rubber composition, the method comprisingincorporating a whey protein component in an amount sufficient toprovide about 0.1 to about 10 phr of whey protein into a rubbercomposition that comprises at least one rubber; and about 5 to about 200phr reinforcing silica filler.
 40. The method of claim 39, wherein theamount of whey protein comprises about 0.5 to about 5 phr.
 41. Themethod of claim 39, further comprising incorporating cellulose ester.42. The method of claim 39, further comprising incorporating starch. 43.The method of claim 39, wherein the whey protein meets at least one ofthe following: a. a majority of the protein chains in the whey proteinhave a molecular weight of greater than about 10 kDaltons; b. a majorityof the proteins in the whey protein are a combination ofalpha-lactalbumin and beta-lactoglobulin; or c. a degree of hydrolysisof less than about 50%.
 44. The method of claim 43, wherein each of (a),(b) and (c) are met.
 45. The method of claim 39, wherein at least amajority (by weight) of the at least one rubber comprises at least oneof: natural rubber, polyisoprene rubber, polybutadiene rubber, andstyrene-butadiene rubber.